Beamforming feedback tone/sub-carrier location within wireless communications

ABSTRACT

An access point (AP) includes at least one processing circuitry configured to support communications with other WDEV(s) and to generate and process signals for such communications. In some examples, the device includes a communication interface and a processing circuitry, among other possible circuitries, components, elements, etc. to support communications with other WDEV(s) and to generate and process signals for such communications. The WDEV transmits a null data packet (NDP) announcement frame that specifies a sub-carrier (SC) or tone grouping factor, a communication channel bandwidth, and other WDEV(s) to respond with beamforming feedback. The WDEV process the NDP announcement frame to determine if it is to respond, and if so, then receives an NDP sounding frame that includes long training fields (LTFs) and pilots at predetermined locations and generates beamforming feedback of communication channel estimates at SCs as determined based on a sub-carrier roster look up table (LUT).

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 120, as a continuation, to U.S. Utility patent applicationSer. No. 15/895,261, entitled “Beamforming feedback tone/sub-carrierlocation within wireless communications,” filed Feb. 13, 2018, which isa continuation to U.S. Utility patent application Ser. No. 15/261,513,entitled “Beamforming feedback tone/sub-carrier location within wirelesscommunications,” filed Sep. 9, 2016, issued as U.S. Pat. No. 9,923,680on Mar. 20, 2018, which claims priority pursuant to 35 U.S.C. § 119(e)to U.S. Provisional Application No. 62/247,701, entitled “Beamformingfeedback tone/sub-carrier location within wireless communications,”filed Oct. 28, 2015; U.S. Provisional Application No. 62/319,487,entitled “Beamforming feedback tone/sub-carrier location within wirelesscommunications,” filed Apr. 7, 2016; and U.S. Provisional ApplicationNo. 62/382,035, entitled “Beamforming feedback tone/sub-carrier locationwithin wireless communications,” filed Aug. 31, 2016, all of which arehereby incorporated herein by reference in their entirety and made partof the present U.S. Utility Patent Application for all purposes.

The U.S. Utility patent application Ser. No. 15/261,513, entitled“Beamforming feedback tone/sub-carrier location within wirelesscommunications,” filed Sep. 9, 2016, issued as U.S. Pat. No. 9,923,680on Mar. 20, 2018, also claims priority pursuant to 35 U.S.C. § 120, as acontinuation-in-part (CIP), to U.S. Utility patent application Ser. No.15/142,431, entitled “Pilot plan and design within OFDM/OFDMA wirelesscommunications,” filed Apr. 29, 2016, issued as U.S. Pat. No. 9,774,428on Sep. 26, 2017, which claims priority pursuant to 35 U.S.C. § 119(e)to U.S. Provisional Application No. 62/170,618, entitled “Sub-carrier ortone plan and design within OFDM/OFDMA wireless communications,” filedJun. 3, 2015; U.S. Provisional Application No. 62/188,426, entitled“Sub-carrier or tone plan and design within OFDM/OFDMA wirelesscommunications,” filed Jul. 2, 2015; U.S. Provisional Application No.62/212,723, entitled “Sub-carrier or tone plan and design withinOFDM/OFDMA wireless communications,” filed Sep. 1, 2015; U.S.Provisional Application No. 62/327,597, entitled “Sub-carrier or toneplan and design within OFDM/OFDMA wireless communications,” filed Apr.26, 2016; and U.S. Provisional Application No. 62/327,904, entitled“Pilot plan and design within OFDM/OFDMA wireless communications,” filedApr. 26, 2016; all of which are hereby incorporated herein by referencein their entirety and made part of the present U.S. Utility PatentApplication for all purposes.

INCORPORATION BY REFERENCE

The following U.S. Utility Patent Application is hereby incorporatedherein by reference in its entirety and made part of the present U.S.Utility Patent Application for all purposes:

1. U.S. Utility patent application Ser. No. 15/142,283, entitled“Sub-carrier or tone plan and design within OFDM/OFDMA wirelesscommunications,” filed on Apr. 29, 2016, issued as U.S. Pat. No.10,003,441 on Jun. 19, 2018.

BACKGROUND Technical Field

The present disclosure relates generally to communication systems; and,more particularly, to beamforming related communications within singleuser, multiple user, multiple access, and/or MIMO wirelesscommunications.

Description of Related Art

Communication systems support wireless and wire lined communicationsbetween wireless and/or wire lined communication devices. The systemscan range from national and/or international cellular telephone systems,to the Internet, to point-to-point in-home wireless networks and canoperate in accordance with one or more communication standards. Forexample, wireless communication systems may operate in accordance withone or more standards including, but not limited to, IEEE 802.11x (wherex may be various extensions such as a, b, n, g, etc.), Bluetooth,advanced mobile phone services (AMPS), digital AMPS, global system formobile communications (GSM), etc., and/or variations thereof.

In some instances, wireless communication is made between a transmitter(TX) and receiver (RX) using single-input-single-output (SISO)communication. Another type of wireless communication issingle-input-multiple-output (SIMO) in which a single TX processes datainto radio frequency (RF) signals that are transmitted to a RX thatincludes two or more antennae and two or more RX paths.

Yet an alternative type of wireless communication ismultiple-input-single-output (MISO) in which a TX includes two or moretransmission paths that each respectively converts a correspondingportion of baseband signals into RF signals, which are transmitted viacorresponding antennae to a RX. Another type of wireless communicationis multiple-input-multiple-output (MIMO) in which a TX and RX eachrespectively includes multiple paths such that a TX parallel processesdata using a spatial and time encoding function to produce two or morestreams of data and a RX receives the multiple RF signals via multipleRX paths that recapture the streams of data utilizing a spatial and timedecoding function.

The number of wireless communication devices implemented andconcurrently operative within wireless communication systems continuesto increase and presents significant challenges for sharing thecommunication medium. The prior art does not provide adequate means bywhich multiple devices can operate efficiently within such communicationsystems. The prior art also does not provide adequate means by whichcoordination may be made between various wireless communication deviceswithin such wireless communication systems.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating an embodiment of a wirelesscommunication system.

FIG. 2A is a diagram illustrating an embodiment of dense deployment ofwireless communication devices.

FIG. 2B is a diagram illustrating an example of communication betweenwireless communication devices.

FIG. 2C is a diagram illustrating another example of communicationbetween wireless communication devices.

FIG. 3A is a diagram illustrating an example of orthogonal frequencydivision multiplexing (OFDM) and/or orthogonal frequency divisionmultiple access (OFDMA).

FIG. 3B is a diagram illustrating another example of OFDM and/or OFDMA.

FIG. 3C is a diagram illustrating another example of OFDM and/or OFDMA.

FIG. 3D is a diagram illustrating another example of OFDM and/or OFDMA.

FIG. 3E is a diagram illustrating an example of single-carrier (SC)signaling.

FIG. 4A is a diagram illustrating an example of an OFDM/A packet.

FIG. 4B is a diagram illustrating another example of an OFDM/A packet ofa second type.

FIG. 4C is a diagram illustrating an example of at least one portion ofan OFDM/A packet of another type.

FIG. 4D is a diagram illustrating another example of an OFDM/A packet ofa third type.

FIG. 4E is a diagram illustrating another example of an OFDM/A packet ofa fourth type.

FIG. 4F is a diagram illustrating another example of an OFDM/A packet.

FIG. 5A is a diagram illustrating another example of an OFDM/A packet.

FIG. 5B is a diagram illustrating another example of an OFDM/A packet.

FIG. 5C is a diagram illustrating another example of an OFDM/A packet.

FIG. 5D is a diagram illustrating another example of an OFDM/A packet.

FIG. 5E is a diagram illustrating another example of an OFDM/A packet.

FIG. 6A is a diagram illustrating an example of selection amongdifferent OFDM/A frame structures for use in communications betweenwireless communication devices and specifically showing OFDM/A framestructures corresponding to one or more resource units (RUs).

FIG. 6B is a diagram illustrating an example of various types ofdifferent resource units (RUs).

FIG. 7A is a diagram illustrating another example of various types ofdifferent RUs.

FIG. 7B is a diagram illustrating another example of various types ofdifferent RUs.

FIG. 7C is a diagram illustrating an example of various types ofcommunication protocol specified physical layer (PHY) fast Fouriertransform (FFT) sizes.

FIG. 7D is a diagram illustrating an example of different channelbandwidths and relationship there between.

FIG. 8A is a diagram illustrating an example of a tone/sub-carrier planshowing pilot locations therein.

FIG. 8B is a diagram illustrating another example of a tone/sub-carrierplan showing pilot locations therein.

FIG. 9A is a diagram illustrating another example of a tone/sub-carrierplan showing pilot locations therein.

FIG. 9B is a diagram illustrating another example of a tone/sub-carrierplan showing pilot locations therein.

FIG. 10A is a diagram illustrating an example of a set of feedbacksub-carrier (SC) locations.

FIG. 10B is a diagram illustrating an example of a feedback SC locationcoinciding with a pilot.

FIG. 10C is a diagram illustrating another example of a feedback SClocation coinciding with a pilot.

FIG. 10D is a diagram illustrating an example of feedback SC locationsfor different respective channel bandwidths (BWs).

FIG. 10E is a diagram illustrating an embodiment of a method forexecution by one or more wireless communication devices.

DETAILED DESCRIPTION

FIG. 1 is a diagram illustrating an embodiment of a wirelesscommunication system 100. The wireless communication system 100 includesbase stations and/or access points 112-116, wireless communicationdevices 118-132 (e.g., wireless stations (STAs)), and a network hardwarecomponent 134. The wireless communication devices 118-132 may be laptopcomputers, or tablets, 118 and 126, personal digital assistants 120 and130, personal computers 124 and 132 and/or cellular telephones 122 and128. Other examples of such wireless communication devices 118-132 couldalso or alternatively include other types of devices that includewireless communication capability. The details of an embodiment of suchwireless communication devices are described in greater detail withreference to FIG. 2B among other diagrams.

Some examples of possible devices that may be implemented to operate inaccordance with any of the various examples, embodiments, options,and/or their equivalents, etc. described herein may include, but are notlimited by, appliances within homes, businesses, etc. such asrefrigerators, microwaves, heaters, heating systems, air conditioners,air conditioning systems, lighting control systems, and/or any othertypes of appliances, etc.; meters such as for natural gas service,electrical service, water service, Internet service, cable and/orsatellite television service, and/or any other types of meteringpurposes, etc.; devices wearable on a user or person including watches,monitors such as those that monitor activity level, bodily functionssuch as heartbeat, breathing, bodily activity, bodily motion or lackthereof, etc.; medical devices including intravenous (IV) medicinedelivery monitoring and/or controlling devices, blood monitoring devices(e.g., glucose monitoring devices) and/or any other types of medicaldevices, etc.; premises monitoring devices such as movementdetection/monitoring devices, door closed/ajar detection/monitoringdevices, security/alarm system monitoring devices, and/or any other typeof premises monitoring devices; multimedia devices includingtelevisions, computers, audio playback devices, video playback devices,and/or any other type of multimedia devices, etc.; and/or generally anyother type(s) of device(s) that include(s) wireless communicationcapability, functionality, circuitry, etc. In general, any device thatis implemented to support wireless communications may be implemented tooperate in accordance with any of the various examples, embodiments,options, and/or their equivalents, etc. described herein.

The base stations (BSs) or access points (APs) 112-116 are operablycoupled to the network hardware 134 via local area network connections136, 138, and 140. The network hardware 134, which may be a router,switch, bridge, modem, system controller, etc., provides a wide areanetwork connection 142 for the communication system 100. Each of thebase stations or access points 112-116 has an associated antenna orantenna array to communicate with the wireless communication devices inits area. Typically, the wireless communication devices register with aparticular base station or access point 112-116 to receive services fromthe communication system 100. For direct connections (i.e.,point-to-point communications), wireless communication devicescommunicate directly via an allocated channel.

Any of the various wireless communication devices (WDEVs) 118-132 andBSs or APs 112-116 may include a processing circuitry and/or acommunication interface to support communications with any other of thewireless communication devices 118-132 and BSs or APs 112-116. In anexample of operation, a processing circuitry and/or a communicationinterface implemented within one of the devices (e.g., any one of theWDEVs 118-132 and BSs or APs 112-116) is/are configured to process atleast one signal received from and/or to generate at least one signal tobe transmitted to another one of the devices (e.g., any other one of theWDEVs 118-132 and BSs or APs 112-116).

Note that general reference to a communication device, such as awireless communication device (e.g., WDEVs) 118-132 and BSs or APs112-116 in FIG. 1, or any other communication devices and/or wirelesscommunication devices may alternatively be made generally herein usingthe term ‘device’ (e.g., with respect to FIG. 2A below, “device 210”when referring to “wireless communication device 210” or “WDEV 210,” or“devices 210-234” when referring to “wireless communication devices210-234”; or with respect to FIG. 2B below, use of “device 310” mayalternatively be used when referring to “wireless communication device310”, or “devices 390 and 391 (or 390-391)” when referring to wirelesscommunication devices 390 and 391 or WDEVs 390 and 391). Generally, suchgeneral references or designations of devices may be usedinterchangeably.

The processing circuitry and/or the communication interface of any oneof the various devices, WDEVs 118-132 and BSs or APs 112-116, may beconfigured to support communications with any other of the variousdevices, WDEVs 118-132 and BSs or APs 112-116. Such communications maybe uni-directional or bi-directional between devices. Also, suchcommunications may be uni-directional between devices at one time andbi-directional between those devices at another time.

In an example, a device (e.g., any one of the WDEVs 118-132 and BSs orAPs 112-116) includes a communication interface and/or a processingcircuitry (and possibly other possible circuitries, components,elements, etc.) to support communications with other device(s) and togenerate and process signals for such communications. The communicationinterface and/or the processing circuitry operate to perform variousoperations and functions to effectuate such communications (e.g., thecommunication interface and the processing circuitry may be configuredto perform certain operation(s) in conjunction with one another,cooperatively, dependently with one another, etc. and other operation(s)separately, independently from one another, etc.). In some examples,such a processing circuitry includes all capability, functionality,and/or circuitry, etc. to perform such operations as described herein.In some other examples, such a communication interface includes allcapability, functionality, and/or circuitry, etc. to perform suchoperations as described herein. In even other examples, such aprocessing circuitry and a communication interface include allcapability, functionality, and/or circuitry, etc. to perform suchoperations as described herein, at least in part, cooperatively with oneanother.

In an example of implementation and operation, BS or AP 116 includes atleast one processing circuitry configured to generate an orthogonalfrequency division multiple access (OFDMA) frame that includes at leastone OFDMA symbol that includes a set of pilots (e.g., at predeterminedlocations such as based on an OFDMA sub-carrier plan). The BS or AP 116then WDEV transmits the OFDMA frame to WDEV 130 and/or the WDEV 132 foruse by the WDEV 130 and/or the WDEV 132 to perform estimation ofcommunication pathway(s) between the BS or AP 116 and the at least oneother WDEV 130 and/or the WDEV 132 using the set of pilots (e.g.,generate beamforming feedback such as for first communication pathwaybetween the BS or AP 116 and the other WDEV 130 and/or a secondcommunication pathway between the BS or AP 116 and the other WDEV 132).

Note that such operations may similarly be performed between the BS orAP 116 and more than one other WDEV, either at the same time ordifferent times (e.g., transmitting the same or different OFDMA framesto both the WDEV 130 and the WDEV 132 at the same time or transmittingdifferent OFDMA frames to the WDEV 130 and the WDEV 132 at differenttimes). In certain examples, the OFDMA sub-carriers are included withina communication channel that has a particular bandwidth (e.g., of 20MHz, 40 MHz, 80 MHz, or 160 MHz, and/or any other desired bandwidth). Insome examples, subsequent communications between the BS or AP 116 andthe WDEV 130 and/or the WDEV 132 may include channel estimation feedbackprovided from the WDEV 130 and/or the WDEV 132 to the BS or AP 116. Inaddition, subsequent communications from the BS or AP 116 and the WDEV130 and/or the WDEV 132 may include beamformed communications that arebased on the channel estimation feedback and/or beamforming feedbackprovided from the WDEV 130 and/or the WDEV 132 to the BS or AP 116. Forexample, the BS or AP 116 transmits a beamformed OFDMA frame to the WDEV130 and/or the WDEV 132.

In another example of implementation and operation, WDEV 130 receives,via a communication channel and from BS or AP 116, a null data packet(NDP) announcement frame (e.g., alternatively referred to as a NDP-A)that specifies a sub-carrier or tone grouping factor, a communicationchannel bandwidth of a group of possible communication channelbandwidths, and at least one wireless communication device to respond tothe BS or AP 116 with beamforming feedback (e.g., such as the WDEV 130).The WDEV 130 then processes the NDP announcement frame, and when it isdetermined that the NDP announcement frame specifies WDEV 130 is torespond to the BS or AP 116 with the beamforming feedback, the WDEV 130receives, via the communication channel and from the BS or AP 116, a NDPsounding frame that includes long training fields (LTFs) and pilots atpredetermined locations. The WDEV 130 then identifies a set of feedbacksub-carrier locations based on the sub-carrier or tone grouping factor(e.g., Ng) and the communication channel bandwidth specified within theNDP announcement frame as applied to a sub-carrier roster look up table(LUT) that specifies sets of feedback sub-carrier locations based onsub-carrier or tone grouping factors and the communication channelbandwidths. The WDEV 130 then processes the NDP sounding frame togenerate the beamforming feedback by estimating the communicationchannel for each sub-carrier location within the set of feedbacksub-carrier locations. The WDEV 130 then transmits, via thecommunication channel, a beamforming feedback frame to the BS or AP 116that includes estimates of the communication channel for eachsub-carrier location within the set of feedback sub-carrier locations.

FIG. 2A is a diagram illustrating an embodiment 201 of dense deploymentof wireless communication devices (shown as WDEVs in the diagram). Anyof the various WDEVs 210-234 may be access points (APs) or wirelessstations (STAs). For example, WDEV 210 may be an AP or an AP-operativeSTA that communicates with WDEVs 212, 214, 216, and 218 that are STAs.WDEV 220 may be an AP or an AP-operative STA that communicates withWDEVs 222, 224, 226, and 228 that are STAs. In certain instances, atleast one additional AP or AP-operative STA may be deployed, such asWDEV 230 that communicates with WDEVs 232 and 234 that are STAs. TheSTAs may be any type of one or more wireless communication device typesincluding wireless communication devices 118-132, and the APs orAP-operative STAs may be any type of one or more wireless communicationdevices including as BSs or APs 112-116. Different groups of the WDEVs210-234 may be partitioned into different basic services sets (BSSs). Insome instances, at least one of the WDEVs 210-234 are included within atleast one overlapping basic services set (OBSS) that cover two or moreBSSs. As described above with the association of WDEVs in an AP-STArelationship, one of the WDEVs may be operative as an AP and certain ofthe WDEVs can be implemented within the same basic services set (BSS).

This disclosure presents novel architectures, methods, approaches, etc.that allow for improved spatial re-use for next generation WiFi orwireless local area network (WLAN) systems. Next generation WiFi systemsare expected to improve performance in dense deployments where manyclients and APs are packed in a given area (e.g., which may be an area[indoor and/or outdoor] with a high density of devices, such as a trainstation, airport, stadium, building, shopping mall, arenas, conventioncenters, colleges, downtown city centers, etc. to name just someexamples). Large numbers of devices operating within a given area can beproblematic if not impossible using prior technologies.

In an example of implementation and operation, WDEV 210 generates atleast one OFDMA frame that includes at least one OFDMA symbol thatincludes a set of pilots based on an OFDMA sub-carrier plan. Such anOFDMA frame may be NDP sounding frame that includes long training fields(LTFs) and pilots at predetermined locations in some examples. The WDEV210 then transmits the OFDMA frame(s) to WDEV 214 and/or the WDEV 218for use by the WDEV 214 and/or the WDEV 218 to perform estimation ofcommunication pathway(s) between the WDEV 210 and the WDEV 214 and/orthe WDEV 218 using the set(s) of pilots within the (e.g., a firstcommunication pathway between the WDEV 210 and the other WDEV 214 and/ora second communication pathway between the WDEV 210 and the other WDEV218).

In another example of implementation and operation, WDEV 214 receives,via a communication channel and from WDEV 210, a null data packet (NDP)announcement frame (e.g., alternatively referred to as a NDP-A) thatspecifies a sub-carrier or tone grouping factor, a communication channelbandwidth of a group of possible communication channel bandwidths, andat least one wireless communication device to respond to the WDEV 210with beamforming feedback (e.g., such as the WDEV 214). The WDEV 214then processes the NDP announcement frame, and when it is determinedthat the NDP announcement frame specifies WDEV 214 is to respond to theWDEV 210 with the beamforming feedback, the WDEV 214 receives, via thecommunication channel and from the WDEV 210, a NDP sounding frame thatincludes long training fields (LTFs) and pilots at predeterminedlocations. The WDEV 214 then identifies a set of feedback sub-carrierlocations based on the sub-carrier or tone grouping factor (e.g., Ng)and the communication channel bandwidth specified within the NDPannouncement frame as applied to a sub-carrier roster look up table(LUT) that specifies sets of feedback sub-carrier locations based onsub-carrier or tone grouping factors and the communication channelbandwidths.

The WDEV 214 then processes the NDP sounding frame to generate thebeamforming feedback by estimating the communication channel for eachsub-carrier location within the set of feedback sub-carrier locations.The WDEV 214 then transmits, via the communication channel, abeamforming feedback frame to the WDEV 210 that includes estimates ofthe communication channel for each sub-carrier location within the setof feedback sub-carrier locations.

FIG. 2B is a diagram illustrating an example 202 of communicationbetween wireless communication devices. A wireless communication device310 (e.g., which may be any one of devices 118-132 as with reference toFIG. 1) is in communication with another wireless communication device390 (and/or any number of other wireless communication devices upthrough another wireless communication device 391) via a transmissionmedium. The wireless communication device 310 includes a communicationinterface 320 to perform transmitting and receiving of at least onesignal, symbol, packet, frame, etc. (e.g., using a transmitter 322 and areceiver 324) (note that general reference to packet or frame may beused interchangeably).

Generally speaking, the communication interface 320 is implemented toperform any such operations of an analog front end (AFE) and/or physicallayer (PHY) transmitter, receiver, and/or transceiver. Examples of suchoperations may include any one or more of various operations includingconversions between the frequency and analog or continuous time domains(e.g., such as the operations performed by a digital to analog converter(DAC) and/or an analog to digital converter (ADC)), gain adjustmentincluding scaling, filtering (e.g., in either the digital or analogdomains), frequency conversion (e.g., such as frequency upscaling and/orfrequency downscaling, such as to a baseband frequency at which one ormore of the components of the device 310 operates), equalization,pre-equalization, metric generation, symbol mapping and/or de-mapping,automatic gain control (AGC) operations, and/or any other operationsthat may be performed by an AFE and/or PHY component within a wirelesscommunication device.

In some implementations, the wireless communication device 310 alsoincludes a processing circuitry 330, and an associated memory 340, toexecute various operations including interpreting at least one signal,symbol, packet, and/or frame transmitted to wireless communicationdevice 390 and/or received from the wireless communication device 390and/or wireless communication device 391. The wireless communicationdevices 310 and 390 (and/or 391) may be implemented using at least oneintegrated circuit in accordance with any desired configuration orcombination of components, modules, etc. within at least one integratedcircuit. Also, the wireless communication devices 310, 390, and/or 391may each include one or more antennas for transmitting and/or receivingof at least one packet or frame (e.g., WDEV 390 may include m antennae,and WDEV 391 may include n antennae).

Also, in some examples, note that one or more of the processingcircuitry 330, the communication interface 320 (including the TX 322and/or RX 324 thereof), and/or the memory 340 may be implemented in oneor more “processing modules,” “processing circuits,” “processors,”and/or “processing units” or their equivalents. Considering one example,one processing circuitry 330 a may be implemented to include theprocessing circuitry 330, the communication interface 320 (including theTX 322 and/or RX 324 thereof), and the memory 340. Considering anotherexample, one processing circuitry 330 b may be implemented to includethe processing circuitry 330 and the memory 340 yet the communicationinterface 320 is a separate circuitry.

Considering even another example, two or more processing circuitries maybe implemented to include the processing circuitry 330, thecommunication interface 320 (including the TX 322 and/or RX 324thereof), and the memory 340. In such examples, such a “processingcircuitry” or “processing circuitries” (or “processor” or “processors”)is/are configured to perform various operations, functions,communications, etc. as described herein. In general, the variouselements, components, etc. shown within the device 310 may beimplemented in any number of “processing modules,” “processingcircuits,” “processors,” and/or “processing units” (e.g., 1, 2, . . . ,and generally using N such “processing modules,” “processing circuits,”“processors,” and/or “processing units”, where N is a positive integergreater than or equal to 1).

In some examples, the device 310 includes both processing circuitry 330and communication interface 320 configured to perform variousoperations. In other examples, the device 310 includes processingcircuitry 330 a configured to perform various operations. In even otherexamples, the device 310 includes processing circuitry 330 b configuredto perform various operations. Generally, such operations includegenerating, transmitting, etc. signals intended for one or more otherdevices (e.g., device 390 through 391) and receiving, processing, etc.other signals received for one or more other devices (e.g., device 390through 391).

In some examples, note that the communication interface 320, which iscoupled to the processing circuitry 330, that is configured to supportcommunications within a satellite communication system, a wirelesscommunication system, a wired communication system, a fiber-opticcommunication system, and/or a mobile communication system (and/or anyother type of communication system implemented using any type ofcommunication medium or media). Any of the signals generated andtransmitted and/or received and processed by the device 310 may becommunicated via any of these types of communication systems.

FIG. 2C is a diagram illustrating another example 203 of communicationbetween wireless communication devices. In an example of operation andimplementation, at or during a first time (e.g., time 1 (□T1)), the WDEV310 transmits signal(s) (e.g., NDP-As, sounding frames, NDP soundingframes, OFDMA frame(s) including pilots, trigger frames, channelestimation feedback, beamforming feedback frames, UL feedback frames,etc.) to WDEV 390, and/or the WDEV 390 transmits other signal(s) to WDEV310. At or during a second time (e.g., time 2 (□T2)), the WDEV 310processes signal(s) (e.g., NDP-As, sounding frames, NDP sounding frames,OFDMA frame(s) including pilots, trigger frames, channel estimationfeedback, beamforming feedback frames, UL feedback frames, etc.)received from WDEV 390, and/or the WDEV 390 processes signal(s) receivedfrom WDEV 310 (e.g., such as by processing of signal(s), channelestimation, feedback, beamformed communications, etc.).

In another example of implementation and operation, WDEV 310 generatesat least one OFDMA frame that includes at least one OFDMA symbol thatincludes at least one set of pilots based on an OFDMA sub-carrier plan.The WDEV 310 then transmits the OFDMA frame(s) to WDEV 390 (and/or theWDEV 391) for use by the WDEV 390 (and/or the WDEV 391) to performestimation of communication pathway(s) between the WDEV 390 (and/or theWDEV 391) using the set(s) of pilots.

Note that different OFDMA frames with different structures and includingdifferent RUs may be transmitted from the WDEV 310 to the WDEV 390(and/or WDEV 391) at the same or different times (e.g., a first OFDMAframe with first pilots for use by the WDEV 390 at or during a firsttime and a second OFDMA frame with second pilots for use by the WDEV 390at or during a second time, or alternatively a single OFDMA frame withpilots for use by both the WDEV 390 and the WDEV 391, or alternatively afirst OFDMA frame with first pilots for use by the WDEV 390 at or duringa first time and a second OFDMA frame with second pilots for use by theWDEV 391 at or during a second time, and/or any other differentcombination thereof, etc.).

In even another example of implementation and operation, WDEV 390receives, via a communication channel and from WDEV 310, a null datapacket (NDP) announcement frame that specifies a sub-carrier or tonegrouping factor, a communication channel bandwidth (e.g., of a number ofpossible or optional communication channel bandwidths), and at least onewireless communication device to respond to the WDEV 310 withbeamforming feedback (e.g., such as the WDEV 390). The WDEV 390 thenprocess the NDP announcement frame, and when it is determined that theNDP announcement frame specifies WDEV 390 is to respond to the WDEV 310with the beamforming feedback, the WDEV 390 then receives, via thecommunication channel and from the WDEV 310, a NDP sounding frame thatincludes long training fields (LTFs) and pilots at predeterminedlocations (e.g., such as based on an OFDMA sub-carrier plan known byboth the WDEV 310 and the WDEV 390). The WDEV 390 then identifies a setof feedback sub-carrier locations based on the sub-carrier or tonegrouping factor and the communication channel bandwidth specified withinthe NDP announcement frame as applied to a sub-carrier roster look uptable (LUT) that specifies sets of feedback sub-carrier locations basedon sub-carrier or tone grouping factors and the communication channelbandwidths. Examples of such sub-carrier roster look up table LUTs areprovided below. The WDEV 390 then processes the NDP sounding frame togenerate the beamforming feedback by estimating the communicationchannel for each sub-carrier location within the set of feedbacksub-carrier locations. The WDEV 390 then transmits, via thecommunication channel, a beamforming feedback frame to the WDEV 310 thatincludes estimates of the communication channel for each sub-carrierlocation within the set of feedback sub-carrier locations.

In some examples, for a feedback sub-carrier location within the set offeedback sub-carrier locations that coincides with a pilot of the pilotsat the predetermined locations, the WDEV 390 also processes the NDPsounding frame to generate the beamforming feedback for a feedbacksub-carrier location within the set of feedback sub-carrier locationsthat coincides with the pilot of the pilots at the predeterminedlocations by interpolating estimates of the communication channel at twosub-carrier locations adjacent to the pilot.

In even other examples, for a feedback sub-carrier location within theset of feedback sub-carrier locations that coincides with a pilot of thepilots at the predetermined locations, the WDEV 390 also processes theNDP sounding frame to generate the beamforming feedback for a feedbacksub-carrier location within the set of feedback sub-carrier locationsthat coincides with the pilot of the pilots at the predeterminedlocations by copying an estimate of the communication channel from asub-carrier location that is adjacent to the pilot.

In another example of operation, the WDEV 390 receives, via thecommunication channel and from the WDEV 310, a trigger frame thatspecifies a time at which to respond to the WDEV 310 with thebeamforming feedback in an uplink (UL) OFDMA frame that also includes atleast one other beamforming feedback from at least one other wirelesscommunication device that is specified by the NDP announcement frame torespond to the WDEV 310 with beamforming feedback. The WDEV 390 thentransmit the beamforming feedback frame to the WDEV 310 that includesthe estimates of the communication channel for the each sub-carrierlocation within the set of feedback sub-carrier locations as part of theUL OFDMA frame at or during the time specified within the trigger frame.

With respect to the sub-carrier roster LUT, for each of the sub-carrieror tone grouping factors, the sub-carrier roster LUT may be designed tospecify a first communication channel bandwidth that includes a 20 MHzcommunication channel bandwidth and a first corresponding set offeedback sub-carrier locations, a second communication channel bandwidththat includes a 40 MHz communication channel bandwidth and a secondcorresponding set of feedback sub-carrier locations that is a subset ofthe first corresponding set of feedback sub-carrier locations, and athird communication channel bandwidth that includes a 80 MHzcommunication channel bandwidth and a third corresponding set offeedback sub-carrier locations that is a subset of the secondcorresponding set of feedback sub-carrier locations. For example, FIG.10D shows one such possible implementation that could be designedaccording to this option.

In some examples, the pilots are at predetermined locations based on anOFDMA sub-carrier plan. In certain embodiments, such a OFDMA sub-carrierplan is characterized by a first OFDMA sub-carrier sub-plan thatincludes first RUs of a first sub-carrier size and first pilots at firstlocations that are substantially uniformly distributed within OFDMAsub-carriers. The OFDMA sub-carrier plan is also characterized by asecond OFDMA sub-carrier sub-plan that includes second RUs of a secondsub-carrier size that is greater than the first sub-carrier size andsecond pilots that includes a same number of pilots as the first pilotsat second locations that are same as the first locations within theOFDMA sub-carriers, and the OFDMA sub-carrier plan is also characterizedby a third OFDMA sub-carrier sub-plan that includes third RUs of a thirdsub-carrier size that is greater than the second sub-carrier size andthird pilots that includes fewer pilots than the second pilots at thirdlocations that include a subset of the first locations within the OFDMAsub-carriers.

In another example of implementation and operation, the WDEV 310includes both a processing circuitry to perform many of the operationsdescribed above and also includes a communication interface, coupled tothe processing circuitry, that is configured to support communicationswithin a satellite communication system, a wireless communicationsystem, a wired communication system, a fiber-optic communicationsystem, and/or a mobile communication system. The processing circuitryis configured to transmit signal(s), communication(s), OFDM symbol(s),OFDM packet(s), OFDMA symbol(s), OFDMA packet(s), and/or any othercommunication(s), etc. to WDEV 390 and/or WDEV 391 via the communicationinterface. In some examples, the processing circuitry is configured toat receive the NDP announcement frame and/or the NDP sounding frame viathe communication interface and/or transmit the beamforming feedbackframe via the communication interface.

FIG. 3A is a diagram illustrating an example 301 of orthogonal frequencydivision multiplexing (OFDM) and/or orthogonal frequency divisionmultiple access (OFDMA). OFDM's modulation may be viewed as dividing upan available spectrum into a plurality of narrowband sub-carriers (e.g.,relatively lower data rate carriers). The sub-carriers are includedwithin an available frequency spectrum portion or band. This availablefrequency spectrum is divided into the sub-carriers or tones used forthe OFDM or OFDMA symbols and packets/frames. Note that sub-carrier ortone may be used interchangeably. Typically, the frequency responses ofthese sub-carriers are non-overlapping and orthogonal. Each sub-carriermay be modulated using any of a variety of modulation coding techniques(e.g., as shown by the vertical axis of modulated data).

A communication device may be configured to perform encoding of one ormore bits to generate one or more coded bits used to generate themodulation data (or generally, data). For example, a processingcircuitry and the communication interface of a communication device maybe configured to perform forward error correction (FEC) and/or errorchecking and correction (ECC) code of one or more bits to generate oneor more coded bits. Examples of FEC and/or ECC may include turbo code,convolutional code, turbo trellis coded modulation (TTCM), low densityparity check (LDPC) code, Reed-Solomon (RS) code, BCH (Bose andRay-Chaudhuri, and Hocquenghem) code, binary convolutional code (BCC),Cyclic Redundancy Check (CRC), and/or any other type of ECC and/or FECcode and/or combination thereof, etc. Note that more than one type ofECC and/or FEC code may be used in any of various implementationsincluding concatenation (e.g., first ECC and/or FEC code followed bysecond ECC and/or FEC code, etc. such as based on an inner code/outercode architecture, etc.), parallel architecture (e.g., such that firstECC and/or FEC code operates on first bits while second ECC and/or FECcode operates on second bits, etc.), and/or any combination thereof. Theone or more coded bits may then undergo modulation or symbol mapping togenerate modulation symbols. The modulation symbols may include dataintended for one or more recipient devices. Note that such modulationsymbols may be generated using any of various types of modulation codingtechniques. Examples of such modulation coding techniques may includebinary phase shift keying (BPSK), quadrature phase shift keying (QPSK),8-phase shift keying (PSK), 16 quadrature amplitude modulation (QAM), 32amplitude and phase shift keying (APSK), etc., uncoded modulation,and/or any other desired types of modulation including higher orderedmodulations that may include even greater number of constellation points(e.g., 1024 QAM, etc.).

FIG. 3B is a diagram illustrating another example 302 of OFDM and/orOFDMA. A transmitting device transmits modulation symbols via thesub-carriers. Note that such modulation symbols may include datamodulation symbols, pilot modulation symbols (e.g., for use in channelestimation, characterization, etc.) and/or other types of modulationsymbols (e.g., with other types of information included therein). OFDMand/or OFDMA modulation may operate by performing simultaneoustransmission of a large number of narrowband carriers (or multi-tones).In some applications, a guard interval (GI) or guard space is sometimesemployed between the various OFDM symbols to try to minimize the effectsof ISI (Inter-Symbol Interference) that may be caused by the effects ofmulti-path within the communication system, which can be particularly ofconcern in wireless communication systems. In addition, a cyclic prefix(CP) and/or cyclic suffix (CS) (shown in right hand side of FIG. 3A)that may be a copy of the CP may also be employed within the guardinterval to allow switching time (e.g., such as when jumping to a newcommunication channel or sub-channel) and to help maintain orthogonalityof the OFDM and/or OFDMA symbols. Generally speaking, an OFDM and/orOFDMA system design is based on the expected delay spread within thecommunication system (e.g., the expected delay spread of thecommunication channel).

In a single-user system in which one or more OFDM symbols or OFDMpackets/frames are transmitted between a transmitter device and areceiver device, all of the sub-carriers or tones are dedicated for usein transmitting modulated data between the transmitter and receiverdevices. In a multiple user system in which one or more OFDM symbols orOFDM packets/frames are transmitted between a transmitter device andmultiple recipient or receiver devices, the various sub-carriers ortones may be mapped to different respective receiver devices asdescribed below with respect to FIG. 3C.

FIG. 3C is a diagram illustrating another example 303 of OFDM and/orOFDMA. Comparing OFDMA to OFDM, OFDMA is a multi-user version of thepopular orthogonal frequency division multiplexing (OFDM) digitalmodulation scheme. Multiple access is achieved in OFDMA by assigningsubsets of sub-carriers to individual recipient devices or users. Forexample, first sub-carrier(s)/tone(s) may be assigned to a user 1,second sub-carrier(s)/tone(s) may be assigned to a user 2, and so on upto any desired number of users. In addition, such sub-carrier/toneassignment may be dynamic among different respective transmissions(e.g., a first assignment for a first packet/frame, a second assignmentfor second packet/frame, etc.). An OFDM packet/frame may include morethan one OFDM symbol. Similarly, an OFDMA packet/frame may include morethan one OFDMA symbol. In addition, such sub-carrier/tone assignment maybe dynamic among different respective symbols within a givenpacket/frame or superframe (e.g., a first assignment for a first OFDMAsymbol within a packet/frame, a second assignment for a second OFDMAsymbol within the packet/frame, etc.). Generally speaking, an OFDMAsymbol is a particular type of OFDM symbol, and general reference toOFDM symbol herein includes both OFDM and OFDMA symbols (and generalreference to OFDM packet/frame herein includes both OFDM and OFDMApackets/frames, and vice versa). FIG. 3C shows example 303 where theassignments of sub-carriers to different users are intermingled amongone another (e.g., sub-carriers assigned to a first user includesnon-adjacent sub-carriers and at least one sub-carrier assigned to asecond user is located in between two sub-carriers assigned to the firstuser). The different groups of sub-carriers associated with each usermay be viewed as being respective channels of a plurality of channelsthat compose all of the available sub-carriers for OFDM signaling.

FIG. 3D is a diagram illustrating another example 304 of OFDM and/orOFDMA. In this example 304, the assignments of sub-carriers to differentusers are located in different groups of adjacent sub-carriers (e.g.,first sub-carriers assigned to a first user include first adjacentlylocated sub-carrier group, second sub-carriers assigned to a second userinclude second adjacently located sub-carrier group, etc.). Thedifferent groups of adjacently located sub-carriers associated with eachuser may be viewed as being respective channels of a plurality ofchannels that compose all of the available sub-carriers for OFDMsignaling.

FIG. 3E is a diagram illustrating an example 305 of single-carrier (SC)signaling. SC signaling, when compared to OFDM signaling, includes asingular relatively wide channel across which signals are transmitted.In contrast, in OFDM, multiple narrowband sub-carriers or narrowbandsub-channels span the available frequency range, bandwidth, or spectrumacross which signals are transmitted within the narrowband sub-carriersor narrowband sub-channels.

Generally, a communication device may be configured to include aprocessing circuitry and the communication interface (or alternatively aprocessing circuitry, such a processing circuitry 330 a and/orprocessing circuitry 330 b shown in FIG. 2B) configured to processreceived OFDM and/or OFDMA symbols and/or frames (and/or SC symbolsand/or frames) and to generate such OFDM and/or OFDMA symbols and/orframes (and/or SC symbols and/or frames).

FIG. 4A is a diagram illustrating an example 401 of an OFDM/A packet.This packet includes at least one preamble symbol followed by at leastone data symbol. The at least one preamble symbol includes informationfor use in identifying, classifying, and/or categorizing the packet forappropriate processing.

FIG. 4B is a diagram illustrating another example 402 of an OFDM/Apacket of a second type. This packet also includes a preamble and data.The preamble is composed of at least one short training field (STF), atleast one long training field (LTF), and at least one signal field(SIG). The data is composed of at least one data field. In both thisexample 402 and the prior example 401, the at least one data symboland/or the at least one data field may generally be referred to as thepayload of the packet. Among other purposes, STFs and LTFs can be usedto assist a device to identify that a frame is about to start, tosynchronize timers, to select an antenna configuration, to set receivergain, to set up certain the modulation parameters for the remainder ofthe packet, to perform channel estimation for uses such as beamforming,etc. In some examples, one or more STFs are used for gain adjustment(e.g., such as automatic gain control (AGC) adjustment), and a given STFmay be repeated one or more times (e.g., repeated 1 time in oneexample). In some examples, one or more LTFs are used for channelestimation, channel characterization, etc. (e.g., such as fordetermining a channel response, a channel transfer function, etc.), anda given LTF may be repeated one or more times (e.g., repeated up to 8times in one example).

Among other purposes, the SIGs can include various information todescribe the OFDM packet including certain attributes as data rate,packet length, number of symbols within the packet, channel width,modulation encoding, modulation coding set (MCS), modulation type,whether the packet as a single or multiuser frame, frame length, etc.among other possible information. This disclosure presents, among otherthings, a means by which a variable length second at least one SIG canbe used to include any desired amount of information. By using at leastone SIG that is a variable length, different amounts of information maybe specified therein to adapt for any situation.

Various examples are described below for possible designs of a preamblefor use in wireless communications as described herein.

FIG. 4C is a diagram illustrating another example 403 of at least oneportion of an OFDM/A packet of another type. A field within the packetmay be copied one or more times therein (e.g., where N is the number oftimes that the field is copied, and N is any positive integer greaterthan or equal to one). This copy may be a cyclically shifted copy. Thecopy may be modified in other ways from the original from which the copyis made.

FIG. 4D is a diagram illustrating another example 404 of an OFDM/Apacket of a third type. In this example 404, the OFDM/A packet includesone or more fields followed by one of more first signal fields (SIG(s)1) followed by one of more second signal fields (SIG(s) 2) followed byand one or more data field.

FIG. 4E is a diagram illustrating another example 405 of an OFDM/Apacket of a fourth type. In this example 405, the OFDM/A packet includesone or more first fields followed by one of more first signal fields(SIG(s) 1) followed by one or more second fields followed by one of moresecond signal fields (SIG(s) 2) followed by and one or more data field.

FIG. 4F is a diagram illustrating another example 406 of an OFDM/Apacket. Such a general preamble format may be backward compatible withprior IEEE 802.11 prior standards, protocols, and/or recommendedpractices.

In this example 406, the OFDM/A packet includes a legacy portion (e.g.,at least one legacy short training field (STF) shown as L-STF, legacysignal field (SIG) shown as L-SIG) and a first signal field (SIG) (e.g.,VHT [Very High Throughput] SIG (shown as SIG-A)). Then, the OFDM/Apacket includes one or more other VHT portions (e.g., VHT short trainingfield (STF) shown as VHT-STF, one or more VHT long training fields(LTFs) shown as VHT-LTF, a second SIG (e.g., VHT SIG (shown as SIG-B)),and one or more data symbols.

Various diagrams below are shown that depict at least a portion (e.g.,preamble) of various OFDM/A packet designs.

FIG. 5A is a diagram illustrating another example 501 of an OFDM/Apacket. In this example 501, the OFDM/A packet includes a signal field(SIG) and/or a repeat of that SIG that corresponds to a prior or legacycommunication standard, protocol, and/or recommended practice relativeto a newer, developing, etc. communication standard, protocol, and/orrecommended practice (shown as L-SIG/R-L-SIG) followed by a first atleast one SIG based on a newer, developing, etc. communication standard,protocol, and/or recommended practice (shown as HE-SIG-AL e.g., where HEcorresponds to high efficiency) followed by a second at least one SIGbased on a newer, developing, etc. communication standard, protocol,and/or recommended practice (shown as HE-SIG-A2, e.g., where HE againcorresponds to high efficiency) followed by a short training field (STF)based on a newer, developing, etc. communication standard, protocol,and/or recommended practice (shown as HE-STF, e.g., where HE againcorresponds to high efficiency) followed by one or more fields.

FIG. 5B is a diagram illustrating another example 502 of an OFDM/Apacket. In this example 502, the OFDM/A packet includes a signal field(SIG) and/or a repeat of that SIG that corresponds to a prior or legacycommunication standard, protocol, and/or recommended practice relativeto a newer, developing, etc. communication standard, protocol, and/orrecommended practice (shown as L-SIG/R-L-SIG) followed by a first atleast one SIG based on a newer, developing, etc. communication standard,protocol, and/or recommended practice (shown as HE-SIG-AL e.g., where HEcorresponds to high efficiency) followed by a second at least one SIGbased on a newer, developing, etc. communication standard, protocol,and/or recommended practice (shown as HE-SIG-A2, e.g., where HE againcorresponds to high efficiency) followed by a third at least one SIGbased on a newer, developing, etc. communication standard, protocol,and/or recommended practice (shown as HE-SIG-A3, e.g., where HE againcorresponds to high efficiency) followed by a fourth at least one SIGbased on a newer, developing, etc. communication standard, protocol,and/or recommended practice (shown as HE-SIG-A4, e.g., where HE againcorresponds to high efficiency) followed by a STF based on a newer,developing, etc. communication standard, protocol, and/or recommendedpractice (shown as HE-STF, e.g., where HE again corresponds to highefficiency) followed by one or more fields.

FIG. 5C is a diagram illustrating another example 502 of an OFDM/Apacket. In this example 503, the OFDM/A packet includes a signal field(SIG) and/or a repeat of that SIG that corresponds to a prior or legacycommunication standard, protocol, and/or recommended practice relativeto a newer, developing, etc. communication standard, protocol, and/orrecommended practice (shown as L-SIG/R-L-SIG) followed by a first atleast one SIG based on a newer, developing, etc. communication standard,protocol, and/or recommended practice (shown as HE-SIG-AL e.g., where HEcorresponds to high efficiency) followed by a second at least one SIGbased on a newer, developing, etc. communication standard, protocol,and/or recommended practice (shown as HE-SIG-A2, e.g., where HE againcorresponds to high efficiency) followed by a third at least one SIGbased on a newer, developing, etc. communication standard, protocol,and/or recommended practice (shown as HE-SIG-B, e.g., where HE againcorresponds to high efficiency) followed by a STF based on a newer,developing, etc. communication standard, protocol, and/or recommendedpractice (shown as HE-STF, e.g., where HE again corresponds to highefficiency) followed by one or more fields. This example 503 shows adistributed SIG design that includes a first at least one SIG-A (e.g.,HE-SIG-A1 and HE-SIG-A2) and a second at least one SIG-B (e.g.,HE-SIG-B).

FIG. 5D is a diagram illustrating another example 504 of an OFDM/Apacket. This example 504 depicts a type of OFDM/A packet that includes apreamble and data. The preamble is composed of at least one shorttraining field (STF), at least one long training field (LTF), and atleast one signal field (SIG).

In this example 504, the preamble is composed of at least one shorttraining field (STF) that corresponds to a prior or legacy communicationstandard, protocol, and/or recommended practice relative to a newer,developing, etc. communication standard, protocol, and/or recommendedpractice (shown as L-STF(s)) followed by at least one long trainingfield (LTF) that corresponds to a prior or legacy communicationstandard, protocol, and/or recommended practice relative to a newer,developing, etc. communication standard, protocol, and/or recommendedpractice (shown as L-LTF(s)) followed by at least one SIG thatcorresponds to a prior or legacy communication standard, protocol,and/or recommended practice relative to a newer, developing, etc.communication standard, protocol, and/or recommended practice (shown asL-SIG(s)) and optionally followed by a repeat (e.g., or cyclicallyshifted repeat) of the L-SIG(s) (shown as RL-SIG(s)) followed by anotherat least one SIG based on a newer, developing, etc. communicationstandard, protocol, and/or recommended practice (shown as HE-SIG-A,e.g., where HE again corresponds to high efficiency) followed by anotherat least one STF based on a newer, developing, etc. communicationstandard, protocol, and/or recommended practice (shown as HE-STF(s),e.g., where HE again corresponds to high efficiency) followed by anotherat least one LTF based on a newer, developing, etc. communicationstandard, protocol, and/or recommended practice (shown as HE-LTF(s),e.g., where HE again corresponds to high efficiency) followed by atleast one packet extension followed by one or more fields.

FIG. 5E is a diagram illustrating another example 505 of an OFDM/Apacket. In this example 505, the preamble is composed of at least onefield followed by at least one SIG that corresponds to a prior or legacycommunication standard, protocol, and/or recommended practice relativeto a newer, developing, etc. communication standard, protocol, and/orrecommended practice (shown as L-SIG(s)) and optionally followed by arepeat (e.g., or cyclically shifted repeat) of the L-SIG(s) (shown asRL-SIG(s)) followed by another at least one SIG based on a newer,developing, etc. communication standard, protocol, and/or recommendedpractice (shown as HE-SIG-A, e.g., where HE again corresponds to highefficiency) followed by one or more fields.

Note that information included in the various fields in the variousexamples provided herein may be encoded using various encoders. In someexamples, two independent binary convolutional code (BCC) encoders areimplemented to encode information corresponding to different respectivemodulation coding sets (MCSs) that are can be selected and/or optimizedwith respect to, among other things, the respective payload on therespective channel. Various communication channel examples are describedwith respect to FIG. 7D below.

Also, in some examples, a wireless communication device generatescontent that is included in the various SIGs (e.g., SIGA and/or SIGB) tosignal MCS(s) to one or more other wireless communication devices toinstruct which MCS(s) for those one or more other wireless communicationdevices to use with respect to one or more communications. In addition,in some examples, content included in a first at least one SIG (e.g.,SIGA) include information to specify at least one operational parameterfor use in processing a second at least one SIG (e.g., SIGB) within thesame OFDM/A packet.

Various OFDM/A frame structures are presented herein for use incommunications between wireless communication devices and specificallyshowing OFDM/A frame structures corresponding to one or more resourceunits (RUs). Such OFDM/A frame structures may include one or more RUs.Note that these various examples may include different total numbers ofsub-carriers, different numbers of data sub-carriers, different numbersof pilot sub-carriers, etc. Different RUs may also have different othercharacteristics (e.g., different spacing between the sub-carriers,different sub-carrier densities, implemented within different frequencybands, etc.).

FIG. 6A is a diagram illustrating an example 601 of selection amongdifferent OFDM/A frame structures for use in communications betweenwireless communication devices and specifically showing OFDM/A framestructures 350 corresponding to one or more resource units (RUs). Thisdiagram may be viewed as having some similarities to allocation ofsub-carriers to different users as shown in FIG. 4D and also shows howeach OFDM/A frame structure is associated with one or more RUs. Notethat these various examples may include different total numbers ofsub-carriers, different numbers of data sub-carriers, different numbersof pilot sub-carriers, etc. Different RUs may also have different othercharacteristics (e.g., different spacing between the sub-carriers,different sub-carrier densities, implemented within different frequencybands, etc.).

In one example, OFDM/A frame structure 1 351 is composed of at least oneRU 1 651. In another example, OFDM/A frame structure 1 351 is composedof at least one RU 1 651 and at least one RU 2 652. In another example,OFDM/A frame structure 1 351 is composed of at least one RU 1 651, atleast one RU 2 652, and at least one RU m 653. Similarly, the OFDM/Aframe structure 2 352 up through OFDM/A frame structure n 353 may becomposed of any combinations of the various RUs (e.g., including any oneor more RU selected from the RU 1 651 through RU m 653).

FIG. 6B is a diagram illustrating an example 602 of various types ofdifferent resource units (RUs). In this example 602, RU 1 651 includesA1 total sub-carrier(s), A2 data (D) sub-carrier(s), A3 pilot (P)sub-carrier(s), and A4 unused sub-carrier(s). RU 2 652 includes B1 totalsub-carrier(s), B2 D sub-carrier(s), B3 P sub-carrier(s), and B4 unusedsub-carrier(s). RU N 653 includes C1 total sub-carrier(s), C2 Dsub-carrier(s), C3 P sub-carrier(s), and C4 unused sub-carrier(s).

Considering the various RUs (e.g., across RU 1 651 to RU N 653), thetotal number of sub-carriers across the RUs increases from RU 1 651 toRU N 653 (e.g., A1<B1<C1). Also, considering the various RUs (e.g.,across RU 1 651 to RU N 653), the ratio of pilot sub-carriers to datasub-carriers across the RUs decreases from RU 1 651 to RU N 653 (e.g.,A3/A2>B3/B2>C3/C2).

In some examples, note that different RUs can include a different numberof total sub-carriers and a different number of data sub-carriers yetinclude a same number of pilot sub-carriers.

As can be seen, this disclosure presents various options for mapping ofdata and pilot sub-carriers (and sometimes unused sub-carriers thatinclude no modulation data or are devoid of modulation data) into OFDMAframes or packets (note that frame and packet may be usedinterchangeably herein) in various communications between communicationdevices including both the uplink (UL) and downlink (DL) such as withrespect to an access point (AP). Note that a user may generally beunderstood to be a wireless communication device implemented in awireless communication system (e.g., a wireless station (STA) or anaccess point (AP) within a wireless local area network (WLAN/WiFi)). Forexample, a user may be viewed as a given wireless communication device(e.g., a wireless station (STA) or an access point (AP), or anAP-operative STA within a wireless communication system). Thisdisclosure discussed localized mapping and distributed mapping of suchsub-carriers or tones with respect to different users in an OFDMAcontext (e.g., such as with respect to FIG. 4C and FIG. 4D includingallocation of sub-carriers to one or more users).

Some versions of the IEEE 802.11 standard have the following physicallayer (PHY) fast Fourier transform (FFT) sizes: 32, 64, 128, 256, 512.

These PHY FFT sizes are mapped to different bandwidths (BWs) (e.g.,which may be achieved using different downclocking ratios or factorsapplied to a first clock signal to generate different other clocksignals such as a second clock signal, a third clock signal, etc.). Inmany locations, this disclosure refers to FFT sizes instead of BW sinceFFT size determines a user's specific allocation of sub-carriers, RUs,etc. and the entire system BW using one or more mappings ofsub-carriers, RUs, etc.

This disclosure presents various ways by which the mapping of N users'sdata into the system BW tones (localized or distributed). For example,if the system BW uses 256 FFT, modulation data for 8 different users caneach use a 32 FFT, respectively. Alternatively, if the system BW uses256 FFT, modulation data for 4 different users can each use a 64 FFT,respectively. In another alternative, if the system BW uses 256 FFT,modulation data for 2 different users can each use a 128 FFT,respectively. Also, any number of other combinations is possible withunequal BW allocated to different users such as 32 FFT to 2 users, 64FFT for one user, and 128 FFT for the last user.

Localized mapping (e.g., contiguous sub-carrier allocations to differentusers such as with reference to FIG. 3D) is preferable for certainapplications such as low mobility users (e.g., that remain stationary orsubstantially stationary and whose location does not change frequently)since each user can be allocated to a sub-band based on at least onecharacteristic. An example of such a characteristic includes allocationto a sub-band that maximizes its performance (e.g., highest SNR orhighest capacity in multi-antenna system). The respective wirelesscommunication devices (users) receive frames or packets (e.g., beacons,null data packet (NDP), data, etc. and/or other frame or packet types)over the entire band and feedback their preferred sub-band or a list ofpreferred sub-bands. Alternatively, a first device (e.g., transmitter,AP, or STA) transmits at least one OFDMA packet to a secondcommunication device, and the second device (e.g., receiver, a STA, oranother STA) may be configured to measure the first device's initialtransmission occupying the entire band and choose a best/good orpreferable sub-band. The second device can be configured to transmit theselection of the information to the first device via feedback, etc.

In some examples, a device is configured to employ PHY designs for 32FFT, 64 FFT and 128 FFT as OFDMA blocks inside of a 256 FFT system BW.When this is done, there can be some unused sub-carriers (e.g., holes ofunused sub-carriers within the provisioned system BW being used). Thiscan also be the case for the lower FFT sizes. In some examples, when anFFT is an integer multiple of another, the larger FFT can be a duplicatea certain number of times of the smaller FFT (e.g., a 512 FFT can be anexact duplicate of two implementations of 256 FFT). In some examples,when using 256 FFT for system BW the available number of tones is 242that can be split among the various users that belong to the OFDMA frameor packet (DL or UL).

In some examples, a PHY design can leave gaps of sub-carriers betweenthe respective wireless communication devices (users) (e.g., unusedsub-carriers). For example, users 1 and 4 may each use a 32 FFTstructure occupying a total of 26×2=52 sub-carriers, user 2 may use a 64FFT occupying 56 sub-carriers and user 3 may use 128 FFT occupying 106sub-carriers adding up to a sum total of 214 sub-carriers leaving 28sub-carriers unused.

In another example, only 32 FFT users are multiplexed allowing up to 9users with 242 sub-carriers−(9 users×26 RUs)=8 unused sub-carriersbetween the users. In yet another example, for 64 FFT users aremultiplexed with 242 sub-carriers−(4 users×56 RUs)=18 unusedsub-carriers.

The unused sub-carriers can be used to provide better separation betweenusers especially in the UL where users's energy can spill into eachother due to imperfect time/frequency/power synchronization creatinginter-carrier interference (ICI).

FIG. 7A is a diagram illustrating another example 701 of various typesof different RUs. In this example 701, RU 1 includes X1 totalsub-carrier(s), X2 data (D) sub-carrier(s), X3 pilot (P) sub-carrier(s),and X4 unused sub-carrier(s). RU 2 includes Y1 total sub-carrier(s), Y2D sub-carrier(s), Y3 P sub-carrier(s), and Y4 unused sub-carrier(s). RUq includes Z1 total sub-carrier(s), Z2 D sub-carrier(s), Z3 Psub-carrier(s), and Z4 unused sub-carrier(s). In this example 701, notethat different RUs can include different spacing between thesub-carriers, different sub-carrier densities, implemented withindifferent frequency bands, span different ranges within at least onefrequency band, etc.

FIG. 7B is a diagram illustrating another example 702 of various typesof different RUs. This diagram shows RU 1 that includes 26 contiguoussub-carriers that include 24 data sub-carriers, and 2 pilotsub-carriers; RU 2 that includes 52 contiguous sub-carriers that include48 data sub-carriers, and 4 pilot sub-carriers; RU 3 that includes 106contiguous sub-carriers that include 102 data sub-carriers, and 4 pilotsub-carriers; RU 4 that includes 242 contiguous sub-carriers thatinclude 234 data sub-carriers, and 8 pilot sub-carriers; RU 5 thatincludes 484 contiguous sub-carriers that include 468 data sub-carriers,and 16 pilot sub-carriers; and RU 6 that includes 996 contiguoussub-carriers that include 980 data sub-carriers, and 16 pilotsub-carriers.

Note that RU 2 and RU 3 include a first/same number of pilotsub-carriers (e.g., 4 pilot sub-carriers each), and RU 5 and RU 6include a second/same number of pilot sub-carriers (e.g., 16 pilotsub-carriers each). The number of pilot sub-carriers remains same orincreases across the RUs. Note also that some of the RUs include aninteger multiple number of sub-carriers of other RUs (e.g., RU 2includes 52 total sub-carriers, which is 2× the 26 total sub-carriers ofRU 1, and RU 5 includes 242 total sub-carriers, which is 2× the 242total sub-carriers of RU 4).

FIG. 7C is a diagram illustrating an example 703 of various types ofcommunication protocol specified physical layer (PHY) fast Fouriertransform (FFT) sizes. The device 310 is configured to generate andtransmit OFDMA packets based on various PHY FFT sizes as specifiedwithin at least one communication protocol. Some examples of PHY FFTsizes, such as based on IEEE 802.11, include PHY FFT sizes such as 32,64, 128, 256, 512, 1024, and/or other sizes.

In one example, the device 310 is configured to generate and transmit anOFDMA packet based on RU 1 that includes 26 contiguous sub-carriers thatinclude 24 data sub-carriers, and 2 pilot sub-carriers and to transmitthat OFDMA packet based on a PHY FFT 32 (e.g., the RU 1 fits within thePHY FFT 32). In one example, the device 310 is configured to generateand transmit an OFDMA packet based on RU 2 that includes 52 contiguoussub-carriers that include 48 data sub-carriers, and 4 pilot sub-carriersand to transmit that OFDMA packet based on a PHY FFT 56 (e.g., the RU 2fits within the PHY FFT 56). The device 310 uses other sized RUs forother sized PHY FFTs based on at least one communication protocol.

Note also that any combination of RUs may be used. In another example,the device 310 is configured to generate and transmit an OFDMA packetbased on two RUs based on RU 1 and one RU based on RU 2 based on a PHYFFT 128 (e.g., two RUs based on RU 1 and one RU based on RU 2 includes atotal of 104 sub-carriers). The device 310 is configured to generate andtransmit any OFDMA packets based on any combination of RUs that can fitwithin an appropriately selected PHY FFT size of at least onecommunication protocol.

Note also that any given RU may be sub-divided or partitioned intosubsets of sub-carriers to carry modulation data for one or more users(e.g., such as with respect to FIG. 3C or FIG. 3D).

FIG. 7D is a diagram illustrating an example 704 of different channelbandwidths and relationship there between. In one example, a device(e.g., the device 310) is configured to generate and transmit any OFDMApacket based on any of a number of OFDMA frame structures within variouscommunication channels having various channel bandwidths. For example, a160 MHz channel may be subdivided into two 80 MHz channels. An 80 MHzchannel may be subdivided into two 40 MHz channels. A 40 MHz channel maybe subdivided into two 20 MHz channels. Note also such channels may belocated within the same frequency band, the same frequency sub-band oralternatively among different frequency bands, different frequencysub-bands, etc.

In certain of the following diagrams, certain explicitly shownindividual sub-carriers represent null tone/sub-carriers (e.g., thosethat include no data/information modulated thereon). Dotted lines areused to show locations of pilots (e.g., predetermined information/datamodulated on these sub-carriers for use in channel estimation,characterization, etc.).

Also, different respective RUs are shown in the various OFDMAtone/sub-carrier plans of the following diagrams such that the numbershown in the diagram for a given RU (e.g., 13, 26, 52, 106, 242, 484,994, 996, etc.) indicates the number of sub-carriers therein (e.g., anRU 13 includes 13 sub-carriers, each being one-half of a RU 26 thatincludes 13 sub-carriers; an RU 26 includes 26 sub-carriers; an RU 52includes 52 sub-carriers, and so on). Note the DC denotes the center ofthe OFDMA sub-carriers of a given OFDMA tone/sub-carrier plan (e.g., thecenter frequency of a given communication channel and/or thosesub-carriers substantially located near the center of the OFDMAsub-carriers, with the horizontal axis showing frequency, sub-carriers(SCs), and/or bandwidth (BW)). Also, note that each respective OFDMAtone/sub-carrier plan includes multiple sub-carrier (SC) sub-plansdepicted in various levels. Generally, when descending in a given OFDMAtone/sub-carrier plan, the size of the respective RUs therein increases.Note that a given SC sub-plan may include RUs of one or two or moredifferent sized-RUs.

FIG. 8A is a diagram illustrating an example 801 of a tone/sub-carrierplan showing pilot locations therein. A 1^(st) SC sub-plan includesmultiple RUs that includes 26 sub-carriers and one sized 26 RU that issplit across DC (e.g., with one respective RU that includes 13sub-carriers on each side of DC). A 2^(nd) SC sub-plan includes multipleRUs that includes 52 sub-carriers and one sized 26 RU that is splitacross DC (e.g., with one respective RU that includes 13 sub-carriers oneach side of DC); note that each RU 52 includes those sub-carriersdirectly included above in 2 RU 26 located directly above in the 1^(st)SC sub-plan. A 3^(rd) SC sub-plan includes multiple RUs that includes106 sub-carriers and one sized 26 RU that is split across DC (e.g., withone respective RU that includes 13 sub-carriers on each side of DC);note that each RU 106 includes those sub-carriers directly includedabove in 2 RU 52 located directly as well as 2 null sub-carriers locatedabove in the 2^(nd) SC sub-plan. A 4^(th) SC sub-plan includes one RUthat includes 242 sub-carriers and spans the OFDMA sub-carriers. In someexamples, the OFDMA tone/sub-carrier plan of this diagram is based on acommunication channel having a bandwidth of 20 MHz. In such a 20 MHzimplementation, the unused sub-carrier locations for 26 tones RU(positive and negative indices) are as follows: 2, 3, 69, 122. As forconstruction of the OFDMA tone/sub-carrier plan in a 20 MHzimplementation, RU-106 aligns with two RU-52 with one unused tone at endand one in the middle.

Also, the pilots (dotted lines) are shown as certain sub-carrierlocations based on the numbers shown above (both positive and negativewith respect to DC). As shown in the diagram, the pilots extend downthrown the various SC sub-plans at least to some extent. For example,pilots at locations +/−116, 90, 48, and 22 extend down from the 1^(st)SC sub-plan to the 4^(th) SC sub-plan. However, note that pilots atlocations +/−102, 76, 62, and 36 extend down from the 1^(st) SC sub-planto only the 2^(nd) SC sub-plan, while pilots at locations +/−10 extenddown from the 1^(st) SC sub-plan to the 3^(rd) SC sub-plan. Similarly,with respect to other OFDMA sub-carrier plans described herein, thepilots and null sub-carriers are shown therein with respect to solid anddotted lines, respectively.

Note that analogous and similar principles of design are used in thefollowing OFDMA tone/sub-carrier plans. The details are shown in thediagrams showing symmetry, construction, design, etc. of the variousOFDMA tone/sub-carrier plans.

FIG. 8B is a diagram illustrating another example 802 of atone/sub-carrier plan showing pilot locations therein. This diagramshows an OFDMA tone/sub-carrier plan with 5 SC sub-plans. Details areshown in the diagram. In some examples, the OFDMA tone/sub-carrier planof this diagram is based on a communication channel having a bandwidthof 40 MHz. In such a 40 MHz implementation, the unused sub-carrierlocations for 26 tones RU (positive and negative indices) are asfollows: 3, 56, 57, 110, 137, 190, 191, 244, where 56 indicates modulo8.

FIG. 9A is a diagram illustrating another example 901 of atone/sub-carrier plan showing pilot locations therein. This diagramshows an OFDMA tone/sub-carrier plan with 6 SC sub-plans. Details areshown in the diagram. In some examples, the OFDMA tone/sub-carrier planof this diagram is based on a communication channel having a bandwidthof 80 MHz. In such an 80 MHz implementation, the unused sub-carrierlocations for 26 tones RU (positive and negative indices) are asfollows: 17, 70, 71, 124, 151, 204, 205, 258, 259, 312, 313, 366, 393,446, 447, 500, where 312 indicates modulo 8.

As for construction of the OFDMA tone/sub-carrier plan in a 40 MHzimplementation, the design involves spreading unused tones for RU-26 andkeeping alignment of two RU-26 with RU-52. As for construction of theOFDMA tone/sub-carrier plan in an 80 MHz implementation relative to the40 MHz implementation, the design involves no change except adding aRU-26 in center of band (e.g., split into two separate RU-13 on eachside of DC).

FIG. 9B is a diagram illustrating another example 902 of atone/sub-carrier plan showing pilot locations therein. This diagramshows an OFDMA tone/sub-carrier plan with 6 SC sub-plans. Details areshown in the diagram. In some examples, the OFDMA tone/sub-carrier planof this diagram is based on a communication channel having a bandwidthof 160 MHz, and this OFDMA tone/sub-carrier plan includes the OFDMAsub-carrier plan of FIG. 9A shown in the left hand side and the righthand side of DC across the communication channel having the bandwidth of160 MHz.

Certain of the various OFDMA tone/sub-carrier plans include a firstOFDMA sub-carrier sub-plan that includes first RUs of a firstsub-carrier size and first null sub-carriers that are distributed acrossthe OFDMA sub-carriers as well as a second OFDMA sub-carrier sub-planthat includes second RUs of a second sub-carrier size that are greaterthan the first sub-carrier size and a second null sub-carriers that aredistributed across the OFDMA sub-carriers such that the second nullsub-carriers are located in common locations as the first nullsub-carriers within the OFDMA sub-carriers.

Across certain of the various OFDMA tone/sub-carrier plans designedaccording to the principles herein, some examples include a first OFDMAsub-carrier sub-plan that includes first RUs of a first sub-carrier sizeand first pilots at first locations that are substantially uniformlydistributed within OFDMA sub-carriers, second OFDMA sub-carrier sub-planthat include second RUs of a second sub-carrier size that is greaterthan the first sub-carrier size and second pilots that includes a samenumber of pilots as the first pilots at second locations that are sameas the first locations within the OFDMA sub-carriers, and a third OFDMAsub-carrier sub-plan that includes third RUs of a third sub-carrier sizethat is greater than the second sub-carrier size and third pilots thatinclude fewer pilots than the second pilots at third locations thatinclude a subset of the first locations within the OFDMA sub-carriers.

In certain examples, the first OFDMA sub-carrier sub-plan includes thefirst RUs of the first sub-carrier size and at least one other RU thatis one-half the first sub-carrier size that are distributed across theOFDMA sub-carriers, the second OFDMA sub-carrier sub-plan that includethe second RUs of the second sub-carrier size that is greater than thefirst sub-carrier size and at least one other RU that is one-half thesecond sub-carrier size that are distributed across the OFDMAsub-carriers, and the third OFDMA sub-carrier sub-plan that includes thethird RUs of the third sub-carrier size that is greater than the secondsub-carrier size and at least one other RU that is one-half the secondsub-carrier size that are distributed across the OFDMA sub-carriers.

In general, with respect to the design of an OFDMA sub-carrier plan thatincludes multiple OFDMA sub-carrier sub-plans therein and selectivelyplaced pilots therein, the design process begins with the OFDMAsub-carrier plan (e.g., including the various RUs of various sizes, etc.along with the placement of the null sub-carriers, etc.), then the pilotlocations are selected so that they will be substantially (and/orapproximately) uniformly distributed within the OFDMA sub-carriers. Inaddition, when dropping down within the OFDMA sub-carrier plan toadditional OFDMA sub-carrier sub-plans (e.g., from 1^(st)/top OFDMAsub-carrier sub-plan that includes relatively smallest sized RUs to a2^(nd)/2^(nd) from top OFDMA sub-carrier sub-plan that includes secondrelatively smallest sized RUs, and so on until the bottom OFDMAsub-carrier sub-plan that includes the relatively largest sized RU(s) inthe OFDMA sub-carrier plan), note that all of the pilot locations do notnecessarily extend all the way from the 1^(st)/top OFDMA sub-carriersub-plan to the bottom OFDMA sub-carrier sub-plan at every location.Note that some of the pilot locations extend down into the OFDMAsub-carrier sub-plan to only a particular depth (e.g., extend from1^(st)/top OFDMA sub-carrier sub-plan to the 2^(nd)/2^(nd) from topOFDMA sub-carrier sub-plan, or extend from 1^(st) hop OFDMA sub-carriersub-plan to the n^(th)/n^(th) from top OFDMA sub-carrier sub-plan, andso on).

The design process is such that when dropping down within the OFDMAsub-carrier plan, and considering that the pilot locations have beenselected to be spread substantially (and/or approximately) uniformlyand/or evenly within the OFDMA sub-carriers, then the design is suchthat the structure is symmetrical (e.g., when mirrored/flipped, fromright (R) to left (L), etc.) so that the overall structure, from OFDMAsub-carrier sub-plan to OFDMA sub-carrier sub-plan across the OFDMAsub-carrier sub-plan, does not have large gaps therein without anypilots.

In addition, as extending down the OFDMA sub-carrier sub-plans withinthe OFDMA sub-carrier sub-plan, the number of pilots within the OFDMAsub-carrier sub-plans can decrease as the size of the RUs of the OFDMAsub-carrier sub-plans increase (e.g., fewer pilots within OFDMAsub-carrier sub-plans that include relatively larger sized RUs). Forexample, in certain OFDMA sub-carrier plans herein, a RU-106 includes102 sub-carriers that carry data and 4 pilots (e.g., pilots carry nodata but instead carry predetermined pilot information therein for usein performing channel estimation). In certain OFDMA sub-carrier plansherein, a RU-242 includes 234 sub-carriers that carry data and 8 pilots.Similarly, as can be seen in the diagrams of various OFDMA sub-carrierplans herein, as the size of the RUs increase within a given OFDMAsub-carrier plan, the number of pilots within such larger RUs decreases.

Note also that even when dropping pilots across the OFDMA sub-carriersub-plans within an OFDMA sub-carrier plan as RU size increases withinthe OFDMA sub-carrier plan, the design operates by trying to maintainthe pilots substantially (and/or approximately) uniformly and/or evenlyspread sub-carriers across the OFDMA sub-carriers bandwidth while tryingto keep even spacing (as much as possible) of the pilots and while alsokeep pilots in same locations (e.g., not moving locations across theOFDMA sub-carrier sub-plans within an OFDMA sub-carrier plan).

Also, when having a predetermined design and location of such pilotsacross the OFDMA sub-carrier plan, then when a WDEV is tracking asignal, that WDEV operate by tracking only the pilots within an RUassigned to it (e.g., only tracking those pilots within one or more RUsassigned to that for use in communications) or the WDEV can track pilotsacross all of the OFDMA sub-carriers (e.g., across the wholecommunication channel, the whole bandwidth, etc.). Also, note that adesign trade-off can be made when moving to OFDMA sub-carrier sub-planshaving relatively larger sized RUs by maintaining a common structure andsymmetry and having less than perfectly uniform coverage of pilots.

In some prior IEEE 802.11 standards, protocols, and/or recommendedpractices, (e.g., the current IEEE 802.11ac design), thetones/sub-carriers used for channel feedback (e.g., compressedbeamforming feedback) with Ng>1 are even values/numberedtons/sub-carriers. For example for 80 MHz, the tones/sub-carriers usedfor feedback with Ng=2 are [−122, −120, −118, −116, −114, −112, −110,−108, −106, −104, −102, −100, −98, −96, −94, −92, −90, −88, −86, −84,−82, −80, −78, −76, −74, −72, −70, −68, −66, −64, −62, −60, −58, −56,−54, −52, −50, −48, −46, −44, −42, −40, −38, −36, −34, −32, −30, −28,−26, −24, −22, −20, −18, −16, −14, −12, −10, −8, −6, −4, −2, 2, 4, 6, 8,10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44,46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80,82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112,114, 116, 118, 120, 122]

The tones/sub-carriers used for feedback with Ng=4 are [−122, −118,−114, −110, −106, −102, −98, −94, −90, −86, −82, 78, −74, −70, −66, −62,−58, −54, −50, −46, −42, −38, −34, −30, −26, −22, −18, −14, −10, −6, −2,2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70,74, 78, 82, 86, 90, 94, 98, 102, 106, 110, 114, 118, 122]

However, note that when operating in accordance with IEEE 802.11ax,pilots occupy even tones and can't directly be used for compressedchannel feedback (e.g., such as with respect to the example 801 for 20MHz shown with reference to FIG. 8A).

This disclosure proposes several solutions for various bandwidths (BWs)including BW=20, 40, 80 MHz. Note that other sized BW(s) (e.g., 160 MHz,and/or any other size of BW) may be constructed following the samedesign solutions.

Solution A

In this option, the beamformee (e.g., receiver, wireless station (STA)receiving a signal from an access point (AP) or another STA, an accesspoint (AP) receiving a signal from another AP or a STA) still uses thesame sub-carrier/tone locations for feedback (e.g., thesub-carriers/tones with even indices descried above tones/sub-carriersused for feedback), but in order to generate the feedback on the pilotsub-carriers/tones, it measures the channel on adjacentsub-carriers/tones and interpolates them to arrive at the requiredestimate.

Note that if the null data packet (NDP) packet uses a 4×LTF (the LTFoccupies all sub-carriers/tones) then adjacent tones to the pilotsub-carriers/tones can be used to estimate the channel on the pilotsub-carriers/tones.

Note that if the NDP packet uses a 2×LTF (the LTF occupies only evensub-carriers/tones) then adjacent even sub-carriers/tones to the pilotsub-carriers/tones can be used to estimate the channel on the pilotsub-carriers/tones.

Solution B

In this option, the beamformee (e.g., receiver, wireless station (STA)receiving a signal from an access point (AP) or another STA, an accesspoint (AP) receiving a signal from another AP or a STA) transfers theinterpolation burden to the beamformer by directly feeding back thechannel in the adjacent sub-carriers/tones to the pilots. In this casethe AP carries out the interpolation.

Note that in this case the feedback overhead increases by the number ofpilots (instead of feeding back the pilot locations, feeding back twolocations around):

For 20 MHz there are 8 pilots and 122 locations for Ng=2, 62 locationsfor Ng=4, 32 locations for Ng=8 [−122:8:−2, 2:8:122]—increasing to 130locations, 70 and 40 locations respectively (6.5%, 13%, 25% increase).

For 40 MHz there are 16 pilots and 242 locations for Ng=2, 122 locationsfor Ng=4 and 62 locations for Ng=8 [−244:8:−4, 4:8:244]—increasing to258 locations, 138 and 78 locations respectively (6.5%, 13% and 25%increase).

For 80 MHz there are 16 pilots and 498 locations for Ng=2, 250 locationsfor Ng=4 and 126 locations for Ng=8 [−500:9:−4 4:8:500]—increasing to514 locations, 266 and 142 locations respectively (3.2%, 6.4% and 12.7%increase).

Solution C

In this option, the beamformee (e.g., receiver, wireless station (STA)receiving a signal from an access point (AP) or another STA, an accesspoint (AP) receiving a signal from another AP or a STA) skips the pilotsub-carriers/tones in the feedback sequence. That means effectively thatan Ng=2 feedback has several locations (equal to the number of pilots)with a gap of 4 sub-carriers/tones hence with performance slightly worsethan Ng=2 and similarly an Ng=4 has several locations (not all locationscollide with pilots) with a gap of 8 sub-carriers/tones hence withperformance slightly worse than Ng=4.

Solution D

In this option, the feedback locations are moved to oddsub-carriers/tones thus avoiding all the pilot locations but with someedge inefficiencies.

For 20 MHz for Ng=2 [−121:2:−3, 3:2:121] with edge sub-carriers/tones[−122 −2 2 122] could be added for improved performance, for Ng=4[−121:4:−5, 5:4:121] with edge sub-carriers/tones [−122 −3 −2 2 3 122]could be added, Ng=8 [−121:8:−9, 9:8:122] with edge sub-carriers/tones[−122 −3 3 122] could be added.

For 40 MHz for Ng=2 [−243:2:−3, 3:2:243], for Ng=4 [−243:4:−3, 3:4:243],for Ng=8 [−243:8:−3, 3:8:243] with edge sub-carriers/tones [−244 244]could be added.

For 80 MHz for Ng=2 [−499:2:−3, 3:2:499], for Ng=4 [−499:4:−3, 3:4:499],for Ng=8 [−499:8:−3, 3:8:499] with edge sub-carriers/tones [−500 500]could be added.

Roster of Feedback Tones for Next Generation (e.g., Developing IEEE802.11Ax)

Certain standards, protocols, and/or recommended practices (e.g., thedeveloping IEEE 802.11ax) have adopted the roster of tones, shown in thetable below, for compressed beamforming feedback. The roster depends onthe null data packet (NDP) Bandwidth (BW) and the tone grouping factor(Ng). This table may be viewed as being an example of a sub-carrierroster look up table (LUT) that specifies sets of feedback sub-carrierlocations based on sub-carrier or tone grouping factors and thecommunication channel bandwidths.

Since the feedback tones are even (e.g., on sub-carriers/tones with evenindices), some of them coincide with pilots. At the pilot tones, the STAinterpolates the channel from neighboring tones before feeding back.Copying the channel on the nearest tone (or one of the nearest tones, ifthere are multiple nearest tones) is a special case of interpolation.

TABLE 1 Roster of tones for feedback Ng = 4 Ng = 16 BW = 20 MHz [−122,−120:4:−4, −2, 2, [−122, −116:16:−4, −2, 4:4:120, 122] 2, 4:16:116, 122]BW = 40 MHz [−244:4:−4, 4:4:244] [−244:16:−4, 4:16:244] BW = 80 MHz[−500:4:−4, 4:4:500] [−500:16:−4, 4:16:500]

Feedback Scheme with OFDMA

When a beamformer (e.g., an AP) wants feedback over bands smaller thanthe NDP bandwidth, 11ax has adopted the following scheme: the beamformer(e.g., AP) will signal the start and end 26 tone RUs that cover thedesired bandwidth.

Using a table, this disclosure defines a start tone associated with eachstart 26 RU and an end tone associated with each end 26 RU. The tabledepends on the NDP BW and Ng.

The beamformee (e.g., an STA) feeds back all tones from the roster thatfall between the start and end tones obtained from the table (thebeamformer (e.g., AP) also signals the tone grouping factor Ng needed tochoose the right table)

TABLE 2a Feedback for Ng = 4 80 MHz 40 MHz 20 MHz 80 MHz (S,E) FB 40 MHz(S,E) FB 20 MHz (S,E) FB 26 RU tone 26 RU tone 26 RU tone 1 −500, −472 1= (S,E) for 2 −476, −448 2 80 MHz + 3 −448, −420 3 256 4 −420, −392 4 5−392, −364 5 6 −368, −340 6 7 −340, −312 7 8 −312, −284 8 9 −288, −260 910 −260, −232 11 −232, −204 12 −204, −176 13 −180, −152 14 −152, −124 15−124, −96  1 −122,−96 16 −100, −72  2 = (S,E) for 17 −72, −44 3 80 MHz +4 18 −44, −16 4 = (S,E) for 19 −16, 16 5 80 MHz 20 16, 44  6 21 44, 72 7 = (S,E) for 22 72, 100 8 80 MHz − 4 23  96, 124 9 96, 122 24 124, 15225 152, 180 26 176, 204 27 204, 232 28 232, 260 29 260, 288 10 = (S,E)for 30 284, 312 11 80 MHz − 31 312, 340 12 256 32 340, 368 13 33 364,392 14 34 392, 420 15 35 420, 448 16 36 448, 476 17 37 472, 500 18

-   -   1. Application of Table 2a above        -   a. beamformer (e.g., AP) signals start and end (S, E) 26 RU        -   b. Pick the s tone for the start RU and the e tone for the            end 26 RU from Table 2a        -   c. Feedback all tones from the feedback roster (Table 1)            between the S and E tones picked in step 1b    -   2. The tones fed back are symmetric around the DC tone

TABLE 2b Feedback for Ng =16 80 MHz 80 MHz 40 MHz 40 MHz 20 MHz 20 MHz26 RU (S,E) FB tone 26 RU (S,E) FB tone 26 RU (S,E) FB tone 1 −500, −4681 = (S,E) for 80 2 −484, −436 2 MHz + 3 −452, −420 3 256 4 −420, −388 45 −404, −356 5 6 −372, −340 6 7 −340, −308 7 8 −324, −276 8 9 −292, −2609 10 −260, −228 11 −244, −196 12 −212, −164 13 −180, −148 14 −164, −11615 −132, −84  1 −122, −84 16 −100, −68  2 = (S,E) for 80 MHz 17 −84, −363 −68, −36 18 −52, −4  4 19 −20, 20 5 = (S,E) for 80 20 4, 52 6 MHz 2136, 84 7 36, 68 22  68, 100 8 = (S,E) for 80 MHz 23  84, 132 9 84, 12224 116, 164 25 148, 180 26 164, 212 27 196, 244 28 228, 260 29 260, 29210 = (S,E) for 80 30 276, 324 11 MHz − 31 308, 340 12 256 32 340, 372 1333 356, 404 14 34 388, 420 15 35 420, 452 16 36 436, 484 17 37 468, 50018

-   -   1. Application of Table 2b above        -   a. AP signals start and end (S, E) 26 RU        -   b. Pick the s tone for the start RU and the e tone for the            end 26 RU from Table 2b        -   c. Feedback all tones from the feedback roster (Table 1)            between the S and E tones picked in step 1b    -   2. The tones fed back are symmetric around the DC tone

Various principles used in such table design (e.g., for a sub-carrierroster look up table (LUT) that specifies sets of feedback sub-carrierlocations based on sub-carrier or tone grouping factors and thecommunication channel bandwidths) are provided below.

Extrapolation Minimized:

For many start 26 RUs, the start tone in the table does not lie withinthe RU, but is in an RU to the “left” (i.e., smaller index). Similarly,for many end 26 RUs, the end tone falls in an RU to the “right” (i.e.,larger index). This operates to ensure that channel estimates on alltones inside the [start, end] 26 RUs can be obtained by interpolationand don't need extrapolation.

Roster Design:

The feedback tone locations are aligned for all NDP bandwidths (i.e.,the roster for 40 MHz is a subset of the roster for 80 MHz. The rosterfor 20 MHz is a subset of the roster for 40 MHz, except for the edgetones ±2, ±122).

Exploiting Symmetries to Condense the Table:

The 26 tone RU locations with 40 MHz NDPs are shifted versions of the 26tone RU locations with 80 MHz NDPs (the shift is ±256, depending onwhether the tones are negative or positive).

Similarly, close to DC, the 26 tone RU locations with 20 MHz NDP areidentical to the 26 tone RU locations with 80 MHz NDP.

The design exploits these symmetries and the fact that the feedback tonelocations are aligned for all bandwidths to reduce the number of entriesin the table.

To do this, the design expresses the (start, end) tones with 20/40 MHzNDPs as shifted versions of the (start, end) tones with 80 MHz NDPs andonly note down the shifts.

FIG. 10A is a diagram illustrating an example 1001 of a set of feedbacksub-carrier (SC) locations. Such a set of feedback SC locations may bedetermined by a wireless communication device by processing an NDPannouncement frame to identify the set of feedback sub-carrier locationsbased on the sub-carrier or tone grouping factor and the communicationchannel bandwidth specified within the NDP announcement frame as appliedto a sub-carrier roster look up table (LUT) that specifies sets offeedback sub-carrier locations based on a plurality of sub-carrier ortone grouping factors and the plurality of communication channelbandwidths. Them, once the set of feedback sub-carrier locations isknown for the particular instance, the wireless communication device canprocess an NDP sounding frame to generate the beamforming feedback byestimating the communication channel for each sub-carrier locationwithin the set of feedback sub-carrier locations and then transmit abeamforming feedback frame (and/or UL OFDMA frame) to the other wirelesscommunication device that includes estimates of the communicationchannel for the each sub-carrier location within the set of feedbacksub-carrier locations as part of the UL OFDMA frame at or during thetime specified within the trigger frame. In some examples, the wirelesscommunication device may transmit such a UL OFDMA frame at or during thetime specified within a previously received trigger frame.

FIG. 10B is a diagram illustrating an example 1002 of a feedback SClocation coinciding with a pilot. When this situation occurs in someexamples, then for a feedback sub-carrier location within the set offeedback sub-carrier locations that coincides with a pilot at least oneof the predetermined locations of the pilots, a wireless communicationdevice operates process the NDP sounding frame to generate thebeamforming feedback for a feedback sub-carrier location within the setof feedback sub-carrier locations that coincides with the pilot at thepredetermined location by interpolating estimates of the communicationchannel at two sub-carrier locations adjacent to the pilot.

In some examples, this involves interpolating using estimates of thecommunication channel at adjacently located sub-carriers (e.g., one oneach side). However, note that estimates of the communication channel atany nearby and/or associated sub-carrier locations may alternatively beused (e.g., using estimate(s) of the communication channel atsub-carrier(s) not adjacently located but instead nearby to the pilot).

FIG. 10C is a diagram illustrating another example 1003 of a feedback SClocation coinciding with a pilot. When this situation occurs in someexamples, then for a feedback sub-carrier location within the set offeedback sub-carrier locations that coincides with a pilot of the set ofpilots at the predetermined locations, process the NDP sounding frame togenerate the beamforming feedback for a feedback sub-carrier locationwithin the set of feedback sub-carrier locations that coincides with thepilot at the predetermined location by copying an estimate of thecommunication channel from a sub-carrier location that is adjacent tothe pilot.

In some examples, this involves copying an estimate the communicationchannel at an adjacently located sub-carrier (e.g., on one of the sidesof the pilot). However, note that another estimate of the communicationchannel at any nearby and/or associated sub-carrier locations mayalternatively be used (e.g., copying an estimate the communicationchannel at a sub-carrier not adjacently located but instead nearby tothe pilot, such as that there may be one or more interveningsub-carriers between the pilot and the sub-carrier location from whichthe estimate the communication channel is copied).

FIG. 10D is a diagram illustrating an example 1004 of feedback SClocations for different respective channel bandwidths (BWs). In thisdiagram, different respective communication channel bandwidths areshown. In some examples, a smaller communication channel bandwidth mayinclude a corresponding set of feedback sub-carrier locations that is asubset of another corresponding set of feedback sub-carrier locationsassociated with a larger bandwidth. For example, a first communicationchannel bandwidth includes a 20 MHz communication channel bandwidth anda first corresponding set of feedback sub-carrier locations, a secondcommunication channel bandwidth includes a 40 MHz communication channelbandwidth and a second corresponding set of feedback sub-carrierlocations that is a subset of the first corresponding set of feedbacksub-carrier locations, and a third communication channel bandwidthincludes a 80 MHz communication channel bandwidth and a thirdcorresponding set of feedback sub-carrier locations that is a subset ofthe second corresponding set of feedback sub-carrier locations.

FIG. 10E is a diagram illustrating an embodiment of a method 1005 forexecution by one or more wireless communication devices. The method 1005operates in step 1010 by receiving (e.g., via a communication interfaceof the wireless communication device) via a communication channel, andfrom another wireless communication device, a null data packet (NDP)announcement frame that specifies a sub-carrier or tone grouping factor,a communication channel bandwidth (of a number of possible or optionalcommunication channel bandwidths), and at least one wirelesscommunication device to respond to the other wireless communicationdevice with beamforming feedback.

The method 1005 continues in step 1020 by processing the NDPannouncement frame (e.g., NDP-A) to determine if the NDP announcementframe specifies the wireless communication device to respond, and whenit is not determined that the NDP announcement frame specifies thewireless communication device is to respond to the other wirelesscommunication device with the beamforming feedback in step 1030 (e.g.,compares unfavorably that the wireless communication device is torespond), the method 1005 may end.

Alternatively when it is determined that the NDP announcement framespecifies the wireless communication device is to respond to the otherwireless communication device with the beamforming feedback in step 1030(e.g., compares favorably that the wireless communication device is torespond), the method 1005 then operates in step 1040 by receiving (e.g.,via the communication interface of the wireless communication device,via the communication channel, and from the other wireless communicationdevice) a NDP sounding frame that includes a long training fields (LTFs)and pilots at predetermined locations. Such predetermined locations forthe pilots may be based on an OFDMA sub-carrier plan such as inaccordance with any of the various examples described herein of theirequivalents (e.g., such as with respect to FIG. 8A, FIG. 8B, FIG. 9A,and/or FIG. 9B).

The method 1005 then operates in step 1050 identifying a set of feedbacksub-carrier locations based on the sub-carrier or tone grouping factorand the communication channel bandwidth specified within the NDPannouncement frame as applied to a sub-carrier roster look up table(LUT) that specifies sets of feedback sub-carrier locations based on aplurality of sub-carrier or tone grouping factors and the plurality ofcommunication channel bandwidths. The method 1005 then operates in step1060 by processing the NDP sounding frame to generate the beamformingfeedback by estimating the communication channel for each sub-carrierlocation within the set of feedback sub-carrier locations. Then, themethod 1005 then operates in step 1070 by transmitting (e.g., via thecommunication interface of the wireless communication device) abeamforming feedback frame to the other wireless communication devicethat includes estimates of the communication channel for eachsub-carrier location within the set of feedback sub-carrier locations.

It is noted that the various operations and functions described withinvarious methods herein may be performed within a wireless communicationdevice (e.g., such as by the processing circuitry 330, communicationinterface 320, and memory 340 or processing circuitry 330 a and/orprocessing circuitry 330 b such as described with reference to FIG. 2B)and/or other components therein. Generally, a communication interfaceand processing circuitry (or alternatively a processing circuitry thatincludes communication interface functionality, components, circuitry,etc.) in a wireless communication device can perform such operations.

Examples of some components may include one of more baseband processingmodules, one or more media access control (MAC) layer components, one ormore physical layer (PHY) components, and/or other components, etc. Forexample, such a processing circuitry can perform baseband processingoperations and can operate in conjunction with a radio, analog front end(AFE), etc. The processing circuitry can generate such signals, packets,frames, and/or equivalents etc. as described herein as well as performvarious operations described herein and/or their respective equivalents.

In some embodiments, such a baseband processing module and/or aprocessing module (which may be implemented in the same device orseparate devices) can perform such processing to generate signals fortransmission to another wireless communication device using any numberof radios and antennae. In some embodiments, such processing isperformed cooperatively by a processing circuitry in a first device andanother processing circuitry within a second device. In otherembodiments, such processing is performed wholly by a processingcircuitry within one device.

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to,” “operably coupled to,” “coupled to,” and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to,” “operable to,” “coupled to,” or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with,” includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably” or equivalent,indicates that a comparison between two or more items, signals, etc.,provides a desired relationship. For example, when the desiredrelationship is that signal 1 has a greater magnitude than signal 2, afavorable comparison may be achieved when the magnitude of signal 1 isgreater than that of signal 2 or when the magnitude of signal 2 is lessthan that of signal 1.

As may also be used herein, the terms “processing module,” “processingcircuit,” “processor,” and/or “processing unit” or their equivalents maybe a single processing device or a plurality of processing devices. Sucha processing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments of an invention have been described above withthe aid of method steps illustrating the performance of specifiedfunctions and relationships thereof. The boundaries and sequence ofthese functional building blocks and method steps have been arbitrarilydefined herein for convenience of description. Alternate boundaries andsequences can be defined so long as the specified functions andrelationships are appropriately performed. Any such alternate boundariesor sequences are thus within the scope and spirit of the claims.Further, the boundaries of these functional building blocks have beenarbitrarily defined for convenience of description. Alternate boundariescould be defined as long as the certain significant functions areappropriately performed. Similarly, flow diagram blocks may also havebeen arbitrarily defined herein to illustrate certain significantfunctionality. To the extent used, the flow diagram block boundaries andsequence could have been defined otherwise and still perform the certainsignificant functionality. Such alternate definitions of both functionalbuilding blocks and flow diagram blocks and sequences are thus withinthe scope and spirit of the claimed invention. One of average skill inthe art will also recognize that the functional building blocks, andother illustrative blocks, modules and components herein, can beimplemented as illustrated or by discrete components, applicationspecific integrated circuits, processing circuitries, processorsexecuting appropriate software and the like or any combination thereof.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples of the invention. A physical embodiment of an apparatus, anarticle of manufacture, a machine, and/or of a process may include oneor more of the aspects, features, concepts, examples, etc. describedwith reference to one or more of the embodiments discussed herein.Further, from figure to figure, the embodiments may incorporate the sameor similarly named functions, steps, modules, etc. that may use the sameor different reference numbers and, as such, the functions, steps,modules, etc. may be the same or similar functions, steps, modules, etc.or different ones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module includes a processing module, a processor, afunctional block, a processing circuitry, hardware, and/or memory thatstores operational instructions for performing one or more functions asmay be described herein. Note that, if the module is implemented viahardware, the hardware may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure of an invention is not limited by the particularexamples disclosed herein and expressly incorporates these othercombinations.

What is claimed is:
 1. An access point (AP) comprises: a communicationinterface; and processing circuitry that is coupled to the communicationinterface, wherein at least one of the communication interface or theprocessing circuitry is configured to: transmit, within a null datapacket (NDP) announcement frame via a communication channel to awireless communication device, a set of feedback sub-carrier locationsbased on a sub-carrier or tone grouping factor and a communicationchannel bandwidth of a plurality of communication channel bandwidths;transmit, via the communication channel to the wireless communicationdevice, an NDP sounding frame that includes a plurality of long trainingfields (LTFs) and a plurality of pilots at predetermined locations; andreceive, via the communication channel from the wireless communicationdevice, a beamforming feedback frame that includes estimates of thecommunication channel for each sub-carrier location within the set offeedback sub-carrier locations based on the NDP sounding frame.
 2. Theaccess point of claim 1, wherein the NDP announcement frame specifies atleast one wireless communication device to respond to the AP withbeamforming feedback.
 3. The access point of claim 1, wherein the atleast one of the communication interface or the processing circuitry isfurther configured to transmit, within the null data packet (NDP)announcement frame via the communication channel to a plurality ofwireless communication devices, the set of feedback sub-carrierlocations based on the sub-carrier or tone grouping factor and thecommunication channel bandwidth of the plurality of communicationchannel bandwidths; and wherein the NDP announcement frame specifies atleast two wireless communication devices to respond to the AP withbeamforming feedback.
 4. The access point of claim 3, wherein the set offeedback sub-carrier locations based on the sub-carrier or tone groupingfactor and the communication channel bandwidth of the plurality ofcommunication channel bandwidths includes specific feedback sub-carrierlocations assigned to each of the at least two wireless communicationdevices.
 5. The access point of claim 1, wherein the set of feedbacksub-carrier locations are based on the sub-carrier or tone groupingfactor and the communication channel bandwidth of the plurality ofcommunication channel bandwidths specified within the NDP announcementframe based on a sub-carrier roster look up table (LUT) that specifiessets of feedback sub-carrier locations based on a plurality ofsub-carrier or tone grouping factors and the plurality of communicationchannel bandwidths.
 6. The access point of claim 5, wherein thesub-carrier roster LUT specifies, for each of the plurality ofsub-carrier or tone grouping factors: a first communication channelbandwidth of the plurality of communication channel bandwidths thatincludes a 20 MHz communication channel bandwidth and a firstcorresponding set of feedback sub-carrier locations; a secondcommunication channel bandwidth of the plurality of communicationchannel bandwidths includes a 40 MHz communication channel bandwidth anda second corresponding set of feedback sub-carrier locations that is asubset of the first corresponding set of feedback sub-carrier locations;and a third communication channel bandwidth of the plurality ofcommunication channel bandwidths includes a 80 MHz communication channelbandwidth and a third corresponding set of feedback sub-carrierlocations that is a subset of the second corresponding set of feedbacksub-carrier locations.
 7. The access point of claim 1, wherein theplurality of pilots at predetermined locations is based on an OFDMAsub-carrier plan that is characterized by: a first OFDMA sub-carriersub-plan that includes a first plurality of resource units (RUs) of afirst sub-carrier size and a first plurality of pilots at firstlocations that are substantially uniformly distributed within aplurality of OFDMA sub-carriers; a second OFDMA sub-carrier sub-planthat includes a second plurality of RUs of a second sub-carrier sizethat is greater than the first sub-carrier size and a second pluralityof pilots that includes a same number of pilots as the first pluralityof pilots at second locations that are same as the first locationswithin the plurality of OFDMA sub-carriers; and a third OFDMAsub-carrier sub-plan that includes a third plurality of RUs of a thirdsub-carrier size that is greater than the second sub-carrier size and athird plurality of pilots that includes fewer pilots than the secondplurality of pilots at third locations that include a subset of thefirst locations within the plurality of OFDMA sub-carriers.
 8. An accesspoint (AP) comprising: a communication interface; and processingcircuitry that is coupled to the communication interface, wherein atleast one of the communication interface or the processing circuitryconfigured to: transmit a null data packet (NDP) announcement frame, viaa communication channel to a plurality of wireless communicationdevices, including a set of feedback sub-carrier locations including asub-carrier or tone grouping factor and a communication channelbandwidth of a plurality of communication channel bandwidths based on asub-carrier roster look up table (LUT) that specifies sets of feedbacksub-carrier locations for specified ones of the plurality of wirelesscommunication devices based on a plurality of sub-carrier or tonegrouping factors and the plurality of communication channel bandwidths;transmit, via a communication channel to the plurality of wirelesscommunication devices, a null data packet (NDP) sounding frame thatincludes a plurality of long training fields (LTFs) and a plurality ofpilots at predetermined locations; transmit, via a communication channelto the plurality of wireless communication devices, a trigger frame thatspecifies a time at which to respond to the AP with beamforming feedbackin an uplink (UL) OFDMA frame and the specified ones of the plurality ofwireless communication devices included in the NDP announcement framethat are to respond to the AP with beamforming feedback; and receive,via the communication channel, a beamforming feedback frame thatincludes estimates of the communication channel for each sub-carrierlocation within the set of feedback sub-carrier locations as part of theUL OFDMA frame at or during the time specified within the trigger frame.9. The access point of claim 8, wherein the set of feedback sub-carrierlocations based on the sub-carrier or tone grouping factor and thecommunication channel bandwidth of the plurality of communicationchannel bandwidths includes specific feedback sub-carrier locationsassigned to each of the specified ones of the plurality of wirelesscommunication devices.
 10. The access point (AP) of claim 8, wherein thesub-carrier roster LUT specifies, for each of the plurality ofsub-carrier or tone grouping factors: a first communication channelbandwidth of the plurality of communication channel bandwidths thatincludes a 20 MHz communication channel bandwidth and a firstcorresponding set of feedback sub-carrier locations; a secondcommunication channel bandwidth of the plurality of communicationchannel bandwidths includes a 40 MHz communication channel bandwidth anda second corresponding set of feedback sub-carrier locations that is asubset of the first corresponding set of feedback sub-carrier locations;and a third communication channel bandwidth of the plurality ofcommunication channel bandwidths includes a 80 MHz communication channelbandwidth and a third corresponding set of feedback sub-carrierlocations that is a subset of the second corresponding set of feedbacksub-carrier locations.
 11. The access point (AP) of claim 8, wherein theplurality of pilots at predetermined locations is based on an OFDMAsub-carrier plan that is characterized by: a first OFDMA sub-carriersub-plan that includes a first plurality of resource units (RUs) of afirst sub-carrier size and a first plurality of pilots at firstlocations that are substantially uniformly distributed within aplurality of OFDMA sub-carriers; a second OFDMA sub-carrier sub-planthat includes a second plurality of RUs of a second sub-carrier sizethat is greater than the first sub-carrier size and a second pluralityof pilots that includes a same number of pilots as the first pluralityof pilots at second locations that are same as the first locationswithin the plurality of OFDMA sub-carriers; and a third OFDMAsub-carrier sub-plan that includes a third plurality of RUs of a thirdsub-carrier size that is greater than the second sub-carrier size and athird plurality of pilots that includes fewer pilots than the secondplurality of pilots at third locations that include a subset of thefirst locations within the plurality of OFDMA sub-carriers.
 12. A methodfor execution by an access point (AP), the method comprising: transmit,within a null data packet (NDP) announcement frame via a communicationchannel to a wireless communication device, a set of feedbacksub-carrier locations based on a sub-carrier or tone grouping factor anda communication channel bandwidth of a plurality of communicationchannel bandwidths; transmit, via the communication channel to thewireless communication device, an NDP sounding frame that includes aplurality of long training fields (LTFs) and a plurality of pilots atpredetermined locations; and receive, via the communication channel fromthe wireless communication device, a beamforming feedback frame thatincludes estimates of the communication channel for each sub-carrierlocation within the set of feedback sub-carrier locations based on theNDP sounding frame.
 13. The method of claim 12, wherein the NDPannouncement frame specifies at least one wireless communication deviceto respond to the AP with beamforming feedback.
 14. The method of claim12 further comprises transmitting, within the null data packet (NDP)announcement frame via the communication channel to a plurality ofwireless communication devices, the set of feedback sub-carrierlocations based on the sub-carrier or tone grouping factor and thecommunication channel bandwidth of the plurality of communicationchannel bandwidths; and wherein the NDP announcement frame specifies atleast two wireless communication devices to respond to the AP withbeamforming feedback.
 15. The method of claim 14, wherein the set offeedback sub-carrier locations based on the sub-carrier or tone groupingfactor and the communication channel bandwidth of the plurality ofcommunication channel bandwidths includes specific feedback sub-carrierlocations assigned to each of the at least two wireless communicationdevices.
 16. The method of claim 12, wherein the set of feedbacksub-carrier locations are based on the sub-carrier or tone groupingfactor and the communication channel bandwidth of the plurality ofcommunication channel bandwidths specified within the NDP announcementframe based on a sub-carrier roster look up table (LUT) that specifiessets of feedback sub-carrier locations based on a plurality ofsub-carrier or tone grouping factors and the plurality of communicationchannel bandwidths.
 17. The method of claim 16, wherein the sub-carrierroster LUT specifies, for each of the plurality of sub-carrier or tonegrouping factors: a first communication channel bandwidth of theplurality of communication channel bandwidths that includes a 20 MHzcommunication channel bandwidth and a first corresponding set offeedback sub-carrier locations; a second communication channel bandwidthof the plurality of communication channel bandwidths includes a 40 MHzcommunication channel bandwidth and a second corresponding set offeedback sub-carrier locations that is a subset of the firstcorresponding set of feedback sub-carrier locations; and a thirdcommunication channel bandwidth of the plurality of communicationchannel bandwidths includes a 80 MHz communication channel bandwidth anda third corresponding set of feedback sub-carrier locations that is asubset of the second corresponding set of feedback sub-carrierlocations.
 18. The method of claim 12, wherein the plurality of pilotsat predetermined locations is based on an OFDMA sub-carrier plan that ischaracterized by: a first OFDMA sub-carrier sub-plan that includes afirst plurality of resource units (RUs) of a first sub-carrier size anda first plurality of pilots at first locations that are substantiallyuniformly distributed within a plurality of OFDMA sub-carriers; a secondOFDMA sub-carrier sub-plan that includes a second plurality of RUs of asecond sub-carrier size that is greater than the first sub-carrier sizeand a second plurality of pilots that includes a same number of pilotsas the first plurality of pilots at second locations that are same asthe first locations within the plurality of OFDMA sub-carriers; and athird OFDMA sub-carrier sub-plan that includes a third plurality of RUsof a third sub-carrier size that is greater than the second sub-carriersize and a third plurality of pilots that includes fewer pilots than thesecond plurality of pilots at third locations that include a subset ofthe first locations within the plurality of OFDMA sub-carriers.